I've never been overly enthusiastic about bench rest shooting, but the cast bullet bench rest shooting sounds kinda interesting. Especially since I haven't a clue as to what type of equipment folks are using. So, if any of you participate in this form of competition, or know anything about it, could you answer a few questions?

What type of cartridges are used, what parent brass, what calibers.

What velocities are being developed.

What alloys are preferred.

What tools are used to bump bullets.

Are there any good webites with info.

TIA

Paul, The Cast Bullet Assoc., both journals & perhaps website should have info. on this. A quick look at the equipment used in the various CBA matches has convinced me (and others) that the organization ss drifting increasingly into the high end BR game. Btw, equipment to bump up CB's is expensive, and according to a report in last year's "Fouling Shot" (their journal), doesn't always produce repeatable results. Moreover, I think the trend is toward "custom" throating with a custom mould which will drop a CB to fit the throat exactly.

Paul,

Thanks, I checked out their website. Unfortunately they don't provide any of their articles on line.

Paul various versions of the 30BR appear to be in vogue now. Bob Lee I think the name is fired a group under .1" in competition this last yr. His chambering I believe is a 30 BR headspaced to the length of the PPC cartridge is lessen case capacity.

I know Lloyd de Vore is right in the middle of competitive shooten. He mentioned using linotype with a 215 gr bullet with a 30BR going 2100-2300. That higher figure for sure a MAX I'd think.

[I hope I spelled Lloyd's last name correctly...]

Maybe Lloyd will pay us a visit and DE-tale some BR information...

[ 03-12-2003, 05:49: Message edited by: aladin ]

I haven't checked for the past couple of months, but I believe the existing Cast Bullet Association record for smallest 5-shot group in a registered BR match is held by Gary Long, of Roseburg, Oregon, at 0.155". It was originally measured at the range by numerous persons at 0.095", but the official measurement is the above figure. I do not know why the over 50% discrepency, but was surprised to see a difference that great.

The previous record was held by David Lee, also of Roseburg, Oregon, at 0.165" 5-shots, 100 yards, center-to-center of widest shots.

The 30-BR is one of the more popular cartridges, and is an outgrowth from the .308 x 1-1/2" cartridges which were at peak popularity about 15 years ago.

Gary Long's record was set with his own version of the .30-PPC, with a reamer ground to his specs by JGS of Coos Bay, Oregon. It was likely inspired by the .30 Kern, which was an "improved PPC" that set records back as far as 1988. Gary Long uses cases necked up from Lapua .220 Russian brass, and fire-formed. He shoots the Eagan MX4-30ARD bullet, of straight linotype, weighing approximately 212-213 grains with Thompson's Blue Angel lube and Hornady gas checks in place.

David Lee's chamber is indeed a .30-BR, with the reamer run in short to establish length using a PPC headspace gauge. David Lee makes his cases on his lathe from Lake City military match brass, as he prefers the Winchester LRP primer for his loads. He uses the same bullet, lube, and gas check as Gary Long.

Gary is still shooting actively. Dave's shooting is in a temporary hiatus as he has recently had a very bad allergic reaction to an antibiotic.

Both shooters prefer their bullets at about 1.950-2000 fps. Gary Long uses VV-N135 as a propellant, while David Lee uses AA 2230-C. Both powders have burning characteristics akin to, but not the exact same as, IMR-4895.

Both shooters are using Nesika Bay actioned rifles...Gary Long's built by Jim Borden, with a CB barrel fitted by David Lee; Dave Lee's rifle is 'smithed by himself. Both shooters are also active jacketed bullet BR shooters, and their CB BR rifles are also used for their jacketed bullet BR shooting. They often shoot in a cast bullet match on Saturday, then switch barrels and shoot the same rifle in 6 PPC, in a jacketed bullet BR match on Sunday.

Sorry - I mis-typed Gary Long's preferred powder. He uses VV-N133 in his .30 PPC, NOT VV-N135.

This Eagan mold design is very similar to Lyman 311644, albeit the '644 carrying more lube. Actually this Eagan/Ardito design inspired the 644 and Lyman has a newer version just out more similar to the MX-4.

Last I heard Eagan molds ran around $80 for a SC but are worth all of that.

Lloyd what kind of throating is being used with these chambers and how much of the bullet is loaded into that throat/leade? TIA and appreciate your input on this thread.

Hi, Aladin

I'll start in a different place than you asked. Both Gary and David mostly use Hart 11" twist barrels, Heavy Varmint contour. Unlike some other prominent makes, these barrels always seem to be almost exactly the same internal bore diameter...a nice, tight, .2998" to about .3000".

Certainly, other makes of barrels may be as consistent from one end to the other, within 0.0001" or 0.0002", but how consistent are they in actual diameter to start with? Some, of a very famous make, vary all over the place, from .2990" to .3020" in diameter. Another I tried recently had a bore diameter of 0.3030"!! If you are trying to shoot a bore-riding nose bullet with a diameter of about .3005", such as the Eagan MX4-30ARD, such barrels may not provide adequate support for the bullet nose. That's particularly true if the alloy is hard and the bullet doesn't slug-up easily or consistently.

The way these barrels are chambered varies from Gary to Dave.

For Gary, the reamer is run in until it headspaces properly on the standard PPC gauge. Gary's JGS reamer has the throat ground so that the bullet barely impinges on the rifling at the tip of the bullet. How many thou that is, I don't know. It is enough it MAY sometimes pull a bullet if the round is unloaded before firing.

For Dave's rifles, a whole different approach is used. Dave uses reamers that are the "standard" JGS .30-BR grind. He used to use mine, then got his own for convenience sake. As near as we can tell, the two are identical.

These JGS .30-BR reamers have a throat ground on them, but it is considerably different than the chamber ends up, being much shorter. We have tried (Gary, David, and I), throat tapers of 1, 1-1/2, 2, and 3-degrees included, using a variety of throating reamers. As a very rough generalization, the 1-degree included taper seems easier to get initial BR-quality accuracy with, but the throats don't last near as long as with the more abrupt tapers...

Anyway, Dave and I chamber our barrels to a case already fireformed in a previous barrel. We chamber with the barrel through the headstock. Run the reamer in until the headspace gauge shows you are about 30-50 thou shy of where you want to be. Then start a "cut and try" approach...cut a few thou deeper, then screw the action on, put the bolt and the "gauge" case in the action, and try to close the bolt. It won't go? Well, unscrew the action, cut a few more thou then try again. We keep doing this until the case will just chamber, with distinct, but light, pressure on the bolt handle during the last 1/4 to 1/3 of its downward travel.

NEEDLESS TO SAY, I HOPE, THIS IS AN EMPTY CASE. NO PRIMER, NO POWDER, NO BULLET!!

Once we have the chamber where it will accept the case, we now put a bullet in the case, seated to where we want it to be in the case neck. Then we run the throating reamer, of whatever taper we want to use, in about 0.125" deeper than the JGS factory reamer has cut its throat. Then, it's the same old "cut & try" all over again, using the case with the bullet in it as a gauge. When the bolt will just close with pressure from about 2/3 closed to all the way closed, you're there.

After a very few barrels, one develops a very good "feel" for how much pressure should be needed to close the bolt.

We do NOT do crush fits of the barrel to the action. That is, we don't crunch the barrel/action joint .003" or some such traditional barrel fitting amount. We just screw the barrels in hand tight, and give the action wrench a gentle "snap" when the barrel shoulder and the front of the reciever ring meet. These are "switch barrel" guns, after all, and we take the barrels on and off perhaps several times per month.

Dave also shoots a "minus" case neck and throat fit. That is, the neck diameter of his chamber is about 0.0001" SMALLER than the diameter of the loaded round. His bullet is also seated out so it is about a 0.0001" interference fit into the tapered throat. DO NOT, FOR ANY REASON, ATTEMPT THIS WITH A JACKETED BULLET GUN, EVER!! AND DO NOT TRY IT WITH A CAST BULLET GUN ON YOUR OWN!! YOU MUST, MUST!!, HAVE AN EXPERIENCED MENTOR TO SHOW YOU EVERY STEP OF THE WAY IF YOU EVER DECIDE TO TRY THIS.

[ 03-14-2003, 22:14: Message edited by: Alberta Canuck ]

Alberta Canuck Thanks for the indepth, informative posting. Very interastin' to this set of ears.

--interference fitting- been there. Only way to get a factory 06 chamber near a tight neck setup. I used a large check dia to accomplish it in an experiement shooten hard ww alloy sans any lube with speed. YOUR WARNING NOT TO ATTEMPT W/O GUIDANCE IS CERTAINLY SOUND ADVICE FOR ANYONE LISTENING IN!

--I'm impressed with the meticulous procedure to chamber your guns. Only way IMO.

--barrel dia's. I know... I did alot of snooping two yrs ago on the 'quiet' trying to decide which tube manufacturer to pick. Wound up I didn't for other reasons, but I couldn't believe the variation I found. If your cutting for a bore rider you have to have nose contact/engravement. You build a gun around a good bullet methinks??

What is the OAL cartridge length of your loaded rds-- or, how much of the bullet is in the throating?

You mention those shallow angled throats not lasting long. How many rds will they take before a setback? Or are setbacks of help?

Myself-- I'd like to go into barrel specifics if your interested. Number of grooves and land heights etc.

Thanks for your very interastin' comments.

Hi, again, Aladin-

Will try to answer some of your questions...one at a time. This will deal with cartridge length, bullet engagment, seating depth.

How long are my .30-BR cartridges overall? Danged if I know...never measured their OAL.

The nose of my bullets usually enters the rifling by about .100" or so, and the bullet nose in my Hart barrels is usually engraved about .00025" to .00050" deep per side. But, after years of using the same bullet in competition, that is almost irrelevant.

What I actually do for benchrest would be a real PITA for some folk.

I've found that Eagan bullets which vary by 0.1 or 0.2 grs wt. in .30 caliber vary significantly in my rifle and my cases as to the effort required to chamber them. Generally speaking, any round which takes more effort to close the bolt is going to go higher on the target at 100 yards than one which takes less pressure to close the bolt. Maybe only 1/8" higher, but higher none-the-less.

As one would suspect, bullets which are lighter take less effort to close the bolt (and shoot lower) than bullets which are heavier.

So, what I do is weigh all my bullets and sort them into groups which weigh the same to 0.1 grain.

When I go to a match, I try to take enough bullets of exactly the same weight & diameter to shoot the whole match and all of the sighters I may need. For a match of 40 shots for record, that is probably about 80-90 bullets, including 3 sighters per target, plus a 10-shot warm-up (sight-in) target at each of 100 and 200 yards.

If I have been lazy and gotten behind in my casting, then hopefully I will have enough bullets of the same weight to shoot 100 yards, and enough bullets of another weight to shoot 200 yards. If I use 2 weights, I always use the heavier bullets at 200 yards.

I also have an assortment of cartridge cases which vary in neck thickness by steps of 0.0001" or less. When I get to the match, I take a bullet of the weight I am going to use and try seating it in the various cases, until I find a case which "feels" right when I seat the bullets into it with my fingers.

I never use a seating die. For my guns and shooting method, the bullet should fit tightly enough that I have to press it into the case firmly with my hand...in fact, tightly enough I can barely press it in with my hand.

Then I shoot the match with that one case, reloading between every shot. As I use a very close case-neck to chamber-neck fit, I never have to resize the case, and I never have to use a seating die. Reloading is simply expelling the old primer, re-priming, throwing a charge directly into the case from my Jones measure, and putting the bullet into the case by hand. I can easily shoot 3 sighters, 5 shots for record, and have 4 or 5 minutes left over in a 10-minute match.

Unlike Dave Lee and Gary Long, I intentionally put a "donut" in my case necks, to use as a bullet seating depth-stop. This is done simply by turning down the outside of the case neck as far as I want the bullet to seat, when I am outside turning to the case thickness desired. Where one quits outside turning, there is a little step on the outside of the case, perhaps .003" or so high. (The turned down portion is .003" smaller in thickness than the unturned portion of the case neck.) When the case is fireformed, that step is transfered to the inside of the case neck, as the cartridge neck is pressed uniformly against the walls of the chamber neck by gas pressure. There is no way anyone can seat a bullet by hand deeper than that .006" step on the inside of the case neck (.003" per side) without using a tool. So, I can't seat the bullet too deeply in the case, and if I haven't seated it deeply enough, the act of chambering the round will complete the seating. It will also insure that bullets of exactly the same weight& diameter will go exactly the same distance into the rifling when they are chambered.

So, I actually can and do choose my cases for both neck tension and seating depth, for each weight of bullet I shoot.

How do I know which case to use? Experience and "feel". I can tell by the pressure it takes to close the bolt on a loaded round if the neck-wall thickness and seating depth are right.

As I mentioned above, this is different than the way Dave and Gary do theirs. They use a traditional neck-sizing die and seating die to control neck tension and seating depth. But the cost they pay for sizing case necks is that their brass doesn't last quite as long. They too each use one case and load between every shot. One can't get better brass consistency than that!

Both methods work equally well. When we shot in competition with each other, which we did frequently until my eyesight failed, we never knew which of us would win. We knew we might very well finish 1, 2, and 3 in the matches we fired in, but we didn't know who would end up in which place. It wasn't unusual for either Dave or Gary to have the smallest group of the day, while I might have the smallest Grand Agg. In score shoots, it all depended on who made the first mistake in reading the wind, but my method did win the Heavy Class Score Championship at the CBA Nationals in both '97 & '98.

Sorry for such a long post.

Best wishes to you.

[ 03-19-2003, 00:37: Message edited by: Alberta Canuck ]

Wow! That answered my questions and then some, also whetted my appetite to build a br cast gun

It also triggered a few more questions:

What type of equipment is used to size and lube bullets? Are bump dies used to even things out? How much are bullets sized, or are they essentially shot as cast? What is the accuracy life of a barrel? How do you clean your bores and how often?

One last one, is there any one or two paticular factors that really make cast bullets shoot, or is it a sum of many factors?

Many thanks for sharing all the great info!

Good questions, Paul.

I have to drive into town right now on my weekly "get supplies" trip, but will try to answer them all when I get back this evening.

Lloyd

[ 03-19-2003, 00:43: Message edited by: Alberta Canuck ]

Hello again y'all...

Paul, before I start to answer your questions, I'd like to say this loud & clear...

RECORD-SETTING ACCURACY CAN BE HAD A NUMBER OF WAYS IN CB SHOOTING!!! THERE IS LIKELY NO ONE "BEST" WAY.

I didn't mean to post that above bit all by itself. Sometimes my computer gets on a jag where it posts all on its lonesome when I hit the space bar, for some unknown reason...

Anyway, what I'm trying to say is that hard alloys driven fast work, but so do soft alloys driven slow. And, doubtless soft lubes work for some approaches, hard lubes for others. One of the hard parts is finding the way that works for you.

Everything I am describing here works for Dave, me, and Gary, but it sure ain't the divine way, given to us by inspiration direct from God.

Now to your questions...as we have approached them in our own shooting:

Sizing & lubing - Dave Lee sizes and lubes with a Star lubricator. He doesn't size much...just sort of kisses the bullet as it goes through the die. He makes his own dies, but I think the one he is using right now is basically a .309" diameter die. The Eagan MX4-30ARD bullet from his moulds drops at about .3095", using pure linotype, so he is hitting it about .00025" per side. Most of the time he throats his barrels with a .309" throating reamer, with a 1-degree included taper, so those .309" bullets are essentially throat size after sizing.

As you may or may not know, Eagan has had several cherries for the MX4-30ARD bullet. His early one likely started out making cavities which threw bullets about .310 in diameter, but by the time Dave's moulds were cut, it was making cavities which threw .3095" bullets.

The reason I bring that up is, recently Don Eagan had a new cherry for that bullet which was cutting cavities which were throwing bullets of .311" nominal diameter. Now I understand that cherry has worn enough that the bullets are somewhat smaller...at least that's what Dave tells me.

Gary Long also uses a Star lubrisizer, but I don't know any of the current details of his sizing or lubing. Initially he did things exactly as Dave does, but as he has shot longer, he has evolved his own modifications.

I size with a Saeco lubricator-sizer. I have two Stars, and tried them but don't like them for CB BR. Mine are now reserved for pistol bullets. That's okay, because I have 5 progressive presses set up for pistol bullets (2 Stars, 2 Dillon 550-B's, 1 Dillon 300), so the Star lubrisizers aren't wasted.

I pre-seat my bullets into the gas checks before putting them in the sizer, but even so, I like a sizer where the bullet comes to a dead stop in the die, down against an immovable ram. I just think it works better to make sure the GC is fully seated. I use a standard Lyman 450 lube-sizer, with an Eagan seater in it (about $10) to seat the GC's on the bullets, then I move to the Saeco to size and lube.

Dave does not pre-seat his bullets into the GC, He seats them by hand and runs them through his Star sizer nose first. I suspect the occasional flyer he gets may be from the GC not being fully seated during sizing, as the nose of the bullet comes up against nothing except the base of the bullet in front of it. As you know, Star sizers push the bullets all the way through the die, not down, then back up.

Lube - For several years I won over David almost every match, even though he is doubtless as good or a better shooter than I am. I attribute that to his having been using too soft a lube for our approach to BR. He used Javelina/Tamarack/any NRA formula 50/50 beeswax/alox lube. It is an excellent lube for some bullets, some barrels, and some velocities, but not for our approach.

I found early on that for my barrels, at the speed I wanted to push my lintoype, hard wax lubes were much better. So, initially, I started using things like the Lyman gold-coloured stuff...can't recall its name. Eventually I went to the hardest of Veral Smith's LBT Blue varieties, with much better results.

Then I tried Thompson's Blue Angel and found it worked almost perfectly for my purposes; just a wee skosh better than the LBT. I finally talked Dave into using the Thompson's, by giving him several sticks when he ran out of his Tamarack lube just before a match. He immediately started shooting scores in the 396-400 range, where before he shot usually in the 388-394 range. His groups also got markedly smaller, and he has never gone away from Blue Angel since. Gary Long also shoots Blue Angel, as do a couple of the other top competitors around here...Chuck Engelking, for one.

As to why Blue Angel or other hard wax lubes work well, I don't know. I have a theory, which makes many knowledgeable folk in the CB world think I'm a total bloody idiot, (and makes them angry for some reason to boot). My theory is that bore/bullet lubrication is not the primary purpose of bullet lube. I suspect its primary purpose is that of a seal. Just like "mud" is used in oil wells to contain pressure and keep gas pressure from blowing out the well, I think bullet lube's most important purpose is to keep high pressure hot powder gas from blowing by, and cutting, bullets. I suspect Blue Angel works better in our cartridges and rifles primarily because it is "stronger" for lack of a better term, and makes a better seal at the interface of the bullet base and the bore.

That's important, perhaps, because we do not use "soft" or"low" pressures to drive our bullets. When you can get 2,200 to 2,300 fps with a 215 gr. .30 bullet out of an 1-1/2" case, you're applying lots of pressure to the bullet's base. Normally we don't shoot quite that hot in competition, more like 1,950 to 2,100 fps, but it still takes plenty of pressure, even with barrels 26" to 29-1/4" long.

Bump dies - For our purposes, the primary use of bump dies is to fit bullets to throats. My best shooting rifle does not require any bumping of my bullets. But, it doesn't shoot the MX4-30ARD. It is set up for a similar Eagan bullet, the MX4-30A, which is about 20 gains lighter. Bump dies are essentially tapered dies which have been specially bored to allow you to decrease or increase the bullet's nose diameter, base diameter, or both, to properly fit a chamber throat.

What is proper fit? Contact everywhere, or even a very, very slight interference fit is probably a good place to start. That's one reason we use straight taper throating reamers when we cut our chambers...it's easy to match that straight tapered throat with a straight taper "bump" die.

My first bump die was used to reshape Ly 314299 bullets to fit the throat of a barrel put on my Wichita action by many time CBA National Champion John Ardito. That barrel had a .3146" diameter at the start of the throat. I tried for months to get it to shoot with bullets sized .311", because I didn't know any better.

When I finally got to the point of throwing rifle and all in the garbage, I gave it instead to the late Larry Jennings, probably one of the best and nicest cast bullet BR shooters who ever lived. I said.."Feel obliged only to return a workable action to me...you can do whatever you want with the rest of it, but please try to make it shoot."

Larry got it to shoot in the high .3"s just by making a chamber cast, then bumping the bullets to fit the .3146" base of the throat and the .302" of the bore. (Bullet base .3146", bullet nose .30225"...Voila!!...Accuracy.)

Bumping is useful for another reason...it allows you to "follow the throat" as it burns out in the barrel over time. You can re-shape the bullet to fit the longer throat.

The down side to bumping is that it is a totally "cut & try" process most of the time. Moving the die in or out a couple of thou can result in very small groups, while another couple of thou can give you very, very large groups. So, it's important to be able to re-set your bump die to the EXACT place that works for each rifle, if you want to use if for more than one gun.

This is getting pretty long, so will come back tomorrow to answer some more questions.

Please remember, though, as said above, THIS WORKS FOR ME, BUT IT IS NOT THE ONLY WAY THAT WORKS.

Best wishes,

Lloyd

[ 03-20-2003, 05:22: Message edited by: Alberta Canuck ]

It was asked earlier if essentially Dave, Gary, and I fit a chamber to a bullet.

Actually, what we do first in setting up a rifle is choose which bullet we would like to shoot, and at what velocity we would like to drive it.

The exact bullet is important for a few reasons: 1) We try to get something easy to cast well; 2) with high quality replacement moulds available on demand; and 3) with a good ballistic coefficient and a shape we think will buck the wind well. Knowing the exact length of the bullet we intend to shoot will also let us calculate the exact rate of rifling twist required in the gun barrel.

Velocity is important because 1) There are several velocity "nodes" at which resistance to wind effects seems to peak; and 2) the velocity required will determine what length and diameter the case needs to be. It appears that with .30-.32 cast bullets wind caused deviation is least somewhere around 1,100 fps (just below sea level speed of sound); again at about 1,900 to 2,100 fps; and again at about 2,950-3,200 fps depending on bullet shape, etc.)

Shooting .30-.32 cast bullets at ca. 3,000 fps with a rifle limited to a max weight of 13.999 lbs. (heavy class) is not a common cup of tea as over the length of a match the recoil will eventually cause some lousy groups for most folk shooting from a bench. So, we choose to shoot our bullets through the 1,900-2,100 fps window. We do that rather than shoot them slow because the 200 yard line is where matches are really won or lost. And the longer the bullet tarries between 100 and 200 yards, the longer the wind has to act on it...push it around.

When we have those two items determined, it is relatively easy to cast a few bullets and from that casting to determine what case neck diameter, case length, throat diameter, barrel twist, bolt face, etc., we want to cut or have cut for us.

Essentially, we are building the whole barrel to fire a specific bullet in a particular velocity range. We may even be picking a specific bolt face for the same reason, depending on the action we plan to use. One of the reasons we like custom actions such as the Nesika Bay Model J, the Kelbly Pandas, the Wichita, and several others, is that the same .308 size bolt face will work to "pull" (extract) either PPC or BR based cartridges. (.220 Russian or .308 Winchester dimension cartridge heads). So will most Remington 700 or 40-X's.

It is easy to get a 215 gr. bullet moving 1,950 fps using a standard 6 PPC case opened to .30 calibre when more than 90% full of VV-N133. With the 6 BR case opened to .30, and using VV-N135, Brig 3032, AA2230, or Win 748, 2,100 and even 2,200 fps is also easy.

I actually prefer to use a 196 gr. bullet at 2,150 or so from the BR case because it seems to be the best compromise for me...grouping ability, wind reading, recoil all taken into acount.

IMPORTANT ACCURACY FACTORS -

The number one factor is probably bullet fit to the chamber throat. The second is consistency. Consistency of everything...cartridge ignition, bullet weight, brass thickness, bench technique, you name it.

Two items I'll say here and then don my Nomex suit.

1. Don't judge a bullet and load by 3 or 4 groups shot on one day. Statistically, that is simply not a big enough sample to test your load and rifle for competition. To parallel what happens with EVERY load in every rifle, take a handful of beans and throw them on the tablecloth on the dining room table (on the cloth so they don't roll around a lot).

Now pick the 5 beans which are closest together and measure that group. Do so for the next 5 closest together beans, and so on until you have measured 4 groups of beans. Then average the groups, and you'll have an aggregate group size. But, it doesn't describe what you really threw down there.

Do the same thing for the 5 widest apart beans, the next 5 widest apart, and so on. Figure the agg for those groups of beans. Still doesn't describe what you threw on the table, does it?

Well, the same is true of rifle bullets shot in groups. If you really want to know what your rifle shoots, try some 100 shot groups.

Obviously, one can wear his barrel(s) out before he ever gets to use them in competition if he goes too far with this. But, what he can do is try shooting three 5-shot groups with the load to be tested, on each of 3 different days...to allow a little bit for varying ambient conditions, whether you have been physically & emotionally up to the task, etc. That'll give you 45 shots in 9 groups to judge from.

2. Any benchrest accuracy testing done without wind flags is a complete and utter waste of time. Shooting without flags is more a test of shooter's luck than of a load's accuracy. Wind moves a 747 jetliner which is flying somewhat slower than a bullet. It moves a space shuttle travelling faster than any rifle bullet. It significantly moves anything that travels through air, whether in ballistic free flight, or carefully guided rocket flight. Why wouldn't it move a bullet?

Wind is never steady for any great length of time. It varies according to everything it passes by, or over, or under. Air moves with a wave motion, just like any other liquid. Sometimes it is at a peak, other times in a trough. Sometimes it eddies and sometimes it forms whirlpools. Only after they've taken that motion into account and aimed acordingly, can anyone assess whether their loads are accurate enough for BR competition purposes.

Learning how to read wind and shoot through it is essential to building the most accurate rifle one's machinery will make. Without that skill, and testing of what one makes, how can it be determined what will increase the rifle's shooting ability? It can't.

CLEANING

Every rifle barrel is a law unto itself.

Bev Pinney was the CBA 1998 Grand National Champion. In the Nationals at KC, Mo., he had to clean his barrel every 5-7 shots because it leaded severely. Cleaning after 5 shots would produce stips of lead fouling that looked like Christmas tree tinsel.

Mel Harris was the 1999 CBA Grand National Champ. His rail gun would get tiny specks of lead in it every few targets. When it did, it would lose accuracy. As it is too late to clean AFTER you've lost a match, Mel would also clean between every target.

My rifle, which won the 1997 CBA Grand National Championship, hated to be cleaned. At the '98 CBA Nationals the first event was a score match at 100 yards. I dropped one point at that distance for a 199/200, and stupidly panicked a bit. I should have just rested easy knowing I would likely pick up on the pack at 200 yards.

But no, I cleaned my rifle, while full-knowing I shouldn't. The next event was 100-yard, 5-shot group targets (4 of them). My first group after cleaning was over an inch!! Then, as my rifle bore "conditioned" again the groups shrank...the 2nd was under an inch, the third well under an inch, and the 4th half an inch. I had just panicked myself out of any chance of winning the '98 Nationals by cleaning a rifle which doesn't like to be cleaned.

The only way to know when to clean any rifle is to listen to what its accuracy tells you. If groups fall off after 12 shots, then you need to clean every 10-12 shots. If the rifle stays accurate for 55 shots, then clean after maybe 50, just to be safe. And so on...

Enough for this time...barrel life, setting back a barrel, etc., next post.

Best wishes,

Lloyd

[ 03-20-2003, 06:00: Message edited by: Alberta Canuck ]

Lloyd, double wow, thanks again for sharing all that dope, and I can't wait for the follow up.

Do any of the competitors use wheelweight metal, or do most/all use lyno or other pure foundry metals?

I'll answer the alloy question today.

Many competitors use various mixtures of alloys. Some use heat-treated wheelweights; many use various mixtures of wheelweights and linotype. Some use monotype; lots of Plain-Based-Bullet Class shooters (no gas checks allowed in PB Class) use straight lead with a very little bit of tin.

All can work well if the rest of the load, chamber, and barrel are fitted to that particular bullet and alloy.

Dave, Gary, and I choose to use straight linotype for a couple of reasons. The least important reason is because we do not have to heat treat linotype to get enough hardness for the velocities, lubes, and bullet shapes we elect to use. WW has a BHN number somewhere around 10-12, Linotype runs about 21 BHN (Brinnell Hardness Number).

The really important reason we use linotype is the word I mentioned in the previous post, "Consistency".

Unless you buy directly from a foundry, you never really know what you are going to get when you buy "pure lead" or "wheelweights". If you bought 5 tons of it all at once, melted it all together in a huge pot, and alloyed it with tin and antimony until you got a metal that works for you, that would be fine.

Most of us don't buy that much at a time, or have the ability to alloy it all together in one huge "melt" even if we did buy that much.

So, Gary, Dave, and I (and many other folks too) shoot straight linotype because it has a very clear formula which was standardized over a century ago by Morgenthaler for use in the line-o-type machines used for automated casting of printing type. That formula is 84% lead, 12% antimony, and 4% tin.

It was developed so that little tiny type, even 8 pt. and smaller, will be crisp, well filled-out, and sharp edged. It will flow into the tiniest nook or cranny of a mould.

It will also be strong (to print many newspapers or books while on a press), and melts at a very low melting point. That low melting point makes it cheaper to use or re-use, and makes it a lot safer for the staff working around it. Lead has a vapour point of about 1000 Fahrenheit. Linotype melts at about 462 F. So, there is no need to heat pure lino to anything like 800 or 900 degrees to cast well with it in most moulds. The lino I use (I buy it 3,000 lbs at a time) casts very, very well at 670 degrees.

Minimal lead vapour during casting means very little chance of lead poisoning if you wash your hands before eating or drinking after handling the alloy.

Other advantages of linotype are that it shrinks less after casting than either pure lead, wheelweights, or any other common bullet casting alloy (other than hard-to-find monotype or stereotype) and it fills out moulds better.

Lastly, linotype is a "eutectic". It does not melt slowly, little bit at a time, nor does it harden that way. Below 462 F. it is all solid. Above 462 F it is all liquid. It is never "slushy". That's what eutectic means in layman's terms...an alloy that melts/hardens all at one temp.

In fact, that is one of the tests for linotype...doing a "cooling curve". Melt a pot of metal and then let it cool, with a casting thermometer in it. If it cools to the mid-500's, then seems to stay the same temp for a bit, then all of a sudden solidifies throughout and drops to 462, it is linotype. If it starts to solidify a little at about 650-700 degrees, then gets more and more solid as it cools on down, it may be lead-based metal, but the metal ain't lino!!

The melting point of pure lead, BTW, is up around 700 degrees...that is, you have to get up around 700 degrees before it is all molten, though it starts getting slushy quite a bit below that figure.

Bottom line is: All lead alloys are legal in CBA competition. There are folks who use just about every imaginable alloy. Gary, Dave & I use linotype for the above described reasons...it's standard, it's simpler, works better for filling out molds, and is safer than most of the others. If we could find monotype easily, we would probably use it, but we can't. Linotype we can find and test for authentication.

Take care in today's risky world, and carpe diem!

[ 03-20-2003, 06:55: Message edited by: Alberta Canuck ]

Sorry I have not been able to address the subject of setting barrels back. Have been busy as a one-armed paper-hanger with hives...

Also have been in no mood to talk since I saw Michael Moore's speech at the academy awards. last night. I believe its content was treasonous, "giving comfort to the enemy" in a time of war....particularly as it was delivered on internationally-watched television. I also believe it was the sour grapes speech of a poor loser who just can't face the reality of his choice having lost the 2000 national election...and whose ego is so big he can't understand that his view is not the national view.

Anyway, to barrels...

RECHAMBERING

Opinions vary all over the map as to whether it is worth while to set barrels back and re-chamber them. The Nosler Reloading Manual Number Two has this in its trouble shooting section, under "9, Worn rifle Barrel."

"Rechamber the rifle. The problem area is usually about 2 inches long, just forward of the chamber. In our lab, we have received excellent service for more than 9,000 rounds by periodic rechambering of the barrel."

On the other hand, Tony Boyer, the greatest benchrest competition shooter who ever lived, has clearly stated several times that he feels life expectancy for PEAK benchrest accuracy is limited to about 800-1,200 rounds. Tony does not believe it is worthwhile to rechamber benchrest barrels for high-stakes competition use. Doubtless Tony's standard of winning competitive benchrest acuracy is much higher than Nosler's requirement for "excellent service" from hunting barrels.

Dave Lee, Gary Long, Mel Harris (1999 CBA Grand National champion) and I have had mixed results.

Using Dave's 17" Hawkeye borescope we find that some barrels which have lost accuracy, have "alligator-skin" surface extending over half the length of the barrel, and the throat has been washed completely away for half an inch or so down the barrel. Such barrels are basically junk at that point. By the time one cut off enough barrel to reach fresh, uncracked rifling, the barrel would be too short to be legal!

On the other hand, some barrels appear basically sound except that the throat has been washed away for a short distance, and the bore is noticably rough for only a short distance just ahead of what was the throat. Those barrels seem worth saving, and sometimes shoot very well after re-chambering.

Usually they do not seem to shoot well for as long a period as they did following the initial chambering, but still may be well worth the effort of cutting off and re-chambering. That seems to be particularly true of barrels which were exceptionally good shooters to begin with. No surprise there, I guess.

The shorter "second life" may be because incipient alligator skin extends further down the barrel than just where it is clearly visible. This possibility only makes sense, as the temperature of the gases travelling down the barrel does not instantly drop in velocity and temperature, from gas-cutting levels to zero, at some sharply-defined point in the barrel. (This is an impression gained from numerous barrels, but is NOT the result of a study done with scientific controls and precision.)

Of course, if one does his own chambering, more "marginal" barrels may be re-fitted economically, and sometimes one is very pleasantly surprised. Other times, though the barrel looks pretty good just down stream of the visible erosion, the results of rechambering are disappointing.

Once in a while, if one just sort of "gnaws" off the breech end of the barrel, rechambering and then test shooting, then rechambering again and test shooting again, all of a sudden the rifle will begin to shoot very well. This, of course, is not a practical approach for those who can't do their own chambering. Even then, if available time is scarce, it may not be practical.

The possibility of rechambering for added useful barrel life is one of the less important reasons we often barrel our rifles with 29" to 29-1/4" long barrels to start with. Cutting them off 2" or so at a time after throats get severely worn could allow two re-cuts in a barrel's life, and still not reduce barrel length below 25". And, of course, if you are just "nibbling at the barrel, it would allow 8 or so re-chamberings, looking for a "sweet" rifling, chamber, barrel-length combo.

BARREL LENGTH

One reason chopping a little length off the barrel may make a difference is the change in the harmonics of the barrel. As with a violin string or tuning fork, changing the length of a free-floating tube or bar changes both frequency and amplitude of its vibrations. Matching barrel frequency and amplitude of motion with the velocity of a bullet, so the bullet always leaves the barrel when the muzzle is in the same part of its swing, will at least theoretically contribute to better accuracy. (Another subject for some day is how to do this by tuning loads to suit the barrel harmonics.)

Just as a note, changing barrel length by chopping the muzzle end off may be even more dramatic in its results, either good or bad. That's particularly true, some suspect, because the button rifling process is very dependent on thoroughly homogenous metal with few inclusions of foreign material, to get a smooth, even rate of twist. Perfectly homogenous and inclusion-free barrel metal is very hard to come by.

Some barrel makers have used bore-scans to develop rifling techniques to make button-rifled barrels which are "regular" in twist for the full length of the barrel. Others apparently haven't (and at about $100 per barrel scan, I can see why!!)

Anyway, it seems to be useful to cut the muzzle of a barrel off at a point where the rate of twist has been very regular for at least an inch or so before the muzzle crown is reached.

HOW LONG DO THROATS (BARRELS) LAST

One of the commonly heard sayings about shooting cast lead bullets is that "you can't wear a barrel out with them". O contraire, mon ami!!

To start with, let's consider what causes most wear in a barrel: (Not necessarily in order of importance)

1. Burn temperature
2. Gas-cutting
3. Bullet friction
4. Corrosion
5. Abrasion

All act by either changing the physical dimensions or the surface characteristics of the bore.

Likely the least important contributor to bore wear is bullet friction. It is not that there is no wear from this cause...just that the rate bullet friction causes wear is so much slower than the other contibutors to barrel damage that the barrel is often a lost cause before bullet friction can do its evil.

My GUESS is that gas cutting probably has the most effect on barrel throats. This can be the result of poor bullet fit to the throat or load intensity (or both). With poor bullet fit to the throat, gas has a chance to race around the bullet into the bore. As the space between the bullet and the bore gets smaller (bullet is starting to fill the bore), the hot gas trying to escape the burning chamber accelerates. The more it accelerates, the greater its cutting ability. If it cuts the bullet, the bore/bullet gap is obturated more slowly and gas cutting of both bullet and barrel continues longer. Which bullet is more likely to be cut by hot gases, lead or jacketed?

Temperature is intimately related to the amount of gas cutting that takes place. Why? Because the higher the temperature the higher the pressure in the chamber...and the higher the pressure, the faster the powder burns and the higher the temperature rises. It is viscious upward cycle of temperature and pressure until either the powder is all consumed or the chamber size expands sufficiently (lengthwise, as the bullet moves down the bore) to let pressure start to drop.

What has that to do with gas cutting of barrel and bullets? The higher the temperature, the more quickly the powder gas expands. And the faster it expands, the more pressure there is forcing the gas through the rapidly closing aperature between barrel and bullet. The decreasing aperature also results in higher gas velocity. So, both temp and resulting pressure contribute directly to gas cutting of the throat/bore areas.

Which has more temp and pressure, cast bullet loads, or jacketed bullet loads? Well, that depends.

In cast bullet rifles shooting plain-based bullets at low velocities out of fairly large chambers using small powder charges, and where low "expansion ratios" exist, one may be able to use a single rifle barrel many thousands of rounds with no practical accuracy loss. Plain base bullets are usually fairly soft so they obturate the bore quickly, which reduces gas cutting. Quick burning powders are often used too, which means the powder burn "dwell" may not last long, which also contributes to less gas cutting of the barrel. Larger bores are also more common, which means a lower expansion ratio and quicker dropping of pressure as the bullet travels down the bore. These are all characteristics of "low intensity" cartridges and loads. Barrels shooting low intensity loads may last a looooong time!!

On the other hand, with cartridges such as the .30-BR, bullets are often hard, driven at double the velocity of low intensity loads, and use relatively slow burning powders in relation to cartridge size.

As a very loose general rule, it requires 4 times the amount of powder to double the velocity of the same bullet from the same case, in the same diameter bore. This means the powder must burn more slowly to avoid pressures in excess of what the action and barrel can withstand. That results in a longer burn time, at the same (or higher) peak pressure as the low intensity load. A long burn time increases the possible gas cutting effect.

At the same time, bullets used in high intensity loads are usually harder, to keep from collapsing totally under the longer dwell (application) of powder gas pressure. Because they are harder, the bullets may not obturate the bore quite as quickly. Slower obturation also means likely increased gas cutting of both bullets & bore.

So, cartridges such as the .30-BR may well develop
gas cutting pressures and temperatures with lead bullet loads which are very much akin to those of jacketed bullet loads of the same velocity in the same cartridge. With the softer, more easily cut bullet alloy, the gas cutting of the barrel may be fully as bad, or perhaps with certain adverse loading formulae, even worse.

Abrasion in cast bullet and jacketed bullet loads is probably about the same with either. Most of the abrasion actually comes from cleaning the bores. "Short stroking" (pumping the cleaning rod in and out with strokes about 6" long") the bore when it still has a lot of carbon in it can abrade the bore by rubbing the carbon debris on the bore. Carbon can be a variety of hardnesses, from graphite to diamonds, and can be a significant abrasive. The higher and longer temp & pressure is applied to carbon, the harder it MAY
be. Dirty cleaning rods used without bore guides can also rub throat and land edges away rapidly if sand or other grit from the range is on them. But generally, there does not seem to be a highly significant difference between abrasive products of jacketed and lead bullets other than the small difference in the amount of hard carbon laid down in the bore, depending on the load.

Corrosion is also similar with both jacketed and cast bullet loads. It is usually a function of the metal used for the barrel, chrome-moly or stainless, and the cleaners & moisture displacers applied to the bore surfaces. Except in black powder rifles, most cast bullet and jacketed bullet rifleman appear to use the same cleaners these days. Corrosion should be about the same.

AGAIN, HOW LONG DO THROATS LAST?

Ultimately, each rifleman will have to determine for himself when the throats of his rifles are sufficiently gone to require barrel chambers to be re-cut or barrels to be replaced.

The closer one comes to requiring bench rest accuracy, and the closer one comes to shooting loads of high intensities (paralleling jacketed-bullet competition loads), the sooner throats and/or barrels will have to be replaced.

With really high intensity CB loads, especially in shallow-angle thoats such as the 1-degree included throats which some are using, PEAK accuracy barrel life may even be as short as Tony Boyer's 800-1,200 rounds generalized barrel life-expectancy.

With lower intensity cast bullet loads, where hunting accuracy will suffice (2 MOA?), some throats/barrels may be re-cut & re-used for much longer "excellent service" than Nosler's 9,000 rounds cited above.

The only way to know for sure of significant barrel change is to keep close recorded track of the average accuracy of one's barrel, per each 100 or 200 rounds fired. When accuracy which was once acceptable begins to drop off, and testing indicates the decreased accuracy is not due to a scope gone "bad", poor shooting technique, or something loose in an otherwise good piece of equipment, it's probably time to cut, rechamber, or rebarrel.

Best wishes all,

AC

[ 03-26-2003, 00:19: Message edited by: Alberta Canuck ]

Lloyd,

Fortunately our boob toob is stored in a closet. I heard about the said idiot, the only solice is he did not recieve any applause.

A co-worker and former marine provided the following quote, which is very poignent.

"It is the soldier, not the reporter who has given us the Freedom of the
press. It is the soldier, not the poet, who has given us the freedom of
speech. It is the soldier, not the campus organizer, who gives us the
freedom to
demonstrate. It is the soldier who salutes the flag, who serves beneath the
flag, and whose coffin is draped by the flag, who allows the protester to
burn the flag." {Authored by Father Dennis Edward O'Brien, Sergeant, USMC)

Thanks for the wonderful dissertation on throats! As with all things gunny, the blanket statements of, barrels last forever when shooting cast doesn't hold true at all, and certainly not for BR guns.

I'll have to start a new thread about a thought I have in regards to a limite run Lee mold, the 160 gr 6.5mm Oldfeller bullet.

If you missed out on the 358-260 gr mold from Lee/Midway, let me know and I'll send some bullets down your way.

I thought I'd bring this thread back up to the top, since the shooters exodus.