I think I just screwed up and bought an RCBS Case Master Tool! My .35 Whelen (semi-custom pre-64 M70 with 21" Douglas barrel with 1/10" twist) has been giving me fits in the accuracy department while working up hunting loads. The rifle has proven that it is a sub MOA often enough that the tight groups were not flukes. The problem is that with the same batch of loads I'll have a nice 3/4" group and then grab another handful of ammo and get a 2-3" group!

So....after I read the thread that Green 788 started on case neck runout experiments I bought the RCBS Case Master Tool. What I found out so far is that my FIRED case exhibit about .001" of runout on the case necks. After sizing these cases some will be as low as .002" and some will be as high as .007" or more! I'm guessing that the case with the extreme runout are cases with uneven neck thickness.

This is basically as far as I've gotten with my investigation (I've only had the tool 2 days). What I have done is seperate the cases into 3 piles: pile #1 has runout of .002" or less, pile #2 has runout of .002"-.004", and pile #3 is everything else.

I guess my question is....am I on the right track and will notice a difference in accuracy? What, in ya'lls experience, is acceptable runout for hunting type loads?

I'm pretty meticulous about my rifle reloading, (case lengths the same, prime pockets clean and uniform, flasholes deburred, etc.), but have never bothered to get this deep into it in all of my 12 or so years of reloading until I was getting unexplained large groups and/or flyers with this rifle. I'm taking this rifle to B.C. for black bear and S. Africa for plains game this year as my primary rifle and it all boils down to the confidence I want to have with this rifle.

I was shocked when I got my RCBS tool too!! What I found out was that my most accurate ammo had .007" runnout and it had just shot a 5 shot penny sized group! I've chased the "runnout gremlin" alot and think I've found him.

#1 make sure you put the shell all the way to the back of the shell holder every time you size. If you get one with alot of runnout resize it again. Push the shell all the way into the die and withdraw it slightly (don't let it get to the expander ball) give it 1/2 turn and push it up into the die and then withdraw it over the expander ball. MY BET IS THE RUNNOUT WILL COME DOWN ALOT.
Lastly if you haven't neck turned your brass and your die is set pretty good you'll probably see about 60-65% of your brass come out of the die at about .002-.003" and under. The rest will fall somewhere between that and .005" but you really shouldn't see rem or win brass worse than .005" if the die is set good.
I have a system for fine tuning the die. You want to get the expander stem as close to the middle of the die as possible. Make small 1/15 turns of the stem and size 5 brass and check runnout. If not good keep making small turns on the sizing stem (always in the same direction up or down) and size 5 more. Keep repeating if necessary and I guarantee you'll find a "sweetspot". and runnout will be good. Hope all this is understandable. thanks don.

Fiddling with the dies and their setting you should be able to get zero runout in the sizing of cases. The issue then is the runout of the seated bullet. If the bullet runout is affected by any runout in the interior of the neck upon seating, you can then segregate, or dump, that case. You can determine that by indexing, pulling, and reseating the same bullet, or by seating another. If the seated bullet is still eccentric, it's probably your case.

Lengthy experiments have been done on the effects of runout in High Power competition. The conclusion is that bullet runout should be less than .002" for "long range" shooting. Beyond this, each .001" of runout opens groups �". Beyond the .002" runout, ammunition is use for "short range". For hunting at ranges less than 200 yards, runout probably doesn't matter. The results of these tests can be found in "Handloading", a publication of the NRA, copyright 1981. Personally I won't use hunting ammo whose runout is more than .001", and zero is preferable. I don't want to be concerned about any more than I have to in making any shot on game. For shorter shots around 100 yards I doubt it would make any difference. However, in the west where shots of 300 yards or more are common, accurate ammo is essential.

Ya'll are scaring the hell outta me!

What causes a a bullet to have more runout than the case? For example; a case with .002" of runout and a bullet runout of .004" or more? Is it a difference in case neck thickness???

As I stand right now...I just bought 50 new cases and plan on doing all my prep work tonight and seperate them into 3 groups according to neck runout; group #1 cases with .002" or less, group #2 cases between .002"-.004", and group #3 cases over .004".

I then plan on working up my loads using the .002" or less cases. Am I on the right track or should I be looking for or doing something else???

This aspect of reloading is totally new to me so I could use all the help I can get!

Thanks Again!

TXPO,
Take the Expander Ball out of your sizing die and size a few cases. the results may surprise you.
Rick

Txpo, I did the same thing after reading Green778 post. Did every thing he said to do and could not get it to go away then I had an idea to check the neck thinkness guess if brass had runout of .004 nick thinkness was off almost the same amount. The next thing was to try and turn necks fire them and resize guess what runout was almost gone all pieces were under .002 and all started out .004 and over. So I am to beleave that if your necks are way out you have three choses through away brass neck turn live with it.Just my findings & were I live it's a long winter to find things like this. give it a try & let me know if it works for you at least check your neck thinkness an compair.

Re: "What causes a a bullet to have more runout than the case?"

Virtually everything you do, from the purchase of the brass to the final seating of the bullet affects concentricity. As to the above question, imagine digging a tight hole for a telephone pole. If the walls of that hole aren't perfectly perpendicular, the pole is going to lean. Same thing with the neck of a case. If the sides of the neck aren't perfectly perpendicular and parallel, even a perfectly seated bullet is going to lean, and that lean could be far more than the runout on the inside of the case.

Bullets themselves can be slightly eccentric. That eccentricity can offset or multiply any runout in the case. The button in the seater can contact the ogive or the tip at an angle and seat the bullet at an slight angle. Kraky's advice re turning a case a half turn is a very good recommendation, not only for sizing but for seating bullets. Also, the fit of the seating button in your seater is very important. Check to see that the button contacts and fits the ogive rather than the tip of the bullet. You can either chuck it in a drill press or grind it with a Dremel tool. The die manufacturers will also make available buttons with a better fit, or adjust yours.

Briefly, I believe you are prepping your cases at the wrong point from what I gather of your intentions. For a perfect round, first of all be sure that the neck walls of the lot of brass you buy are reasonably uniform. First thing I do when buying new brass is to mike the walls. If the variance is more than .0015" in the walls, I either dump the brass, sell it to a less discriminating reloader, or sell it at a gun show, then buy another lot. Too much good brass is made to fiddle with sub-standard stuff. .0015" variance is my absolute top limit.

Having started with good brass, the only thing I do before fire forming, is to uniform the primer pockets. After fire forming I perform all the other prep, principally because the brass will blow out, the trim lengths will immediately vary after you do so, and you'd have to trim again to get them all uniform. Do it once after the fireforming. After that I trim, deburr the flashholes, then weigh and segregate after the uniforming. I then proceed to size and load. I don't turn necks as that is counterproductive to accuracy in all but tight necked chambers and I DO use bushing dies without expander.

There are books written on the subject of building a perfect round. Sinclair has a couple, one from Precision Shooting and their own. I'd suggest purchasing either, or both. They both have volumes of information on the subject of reloading for extreme accuracy. Now that you have your concentricity gauge, you'd do well to do so. Lots of good advice in there.

Or, you can send your concentricty back for a refund and not worry about the little things!!

[ 01-24-2003, 02:59: Message edited by: Bob338 ]

For what it's worth I think you may be chasing the wrong rabbit on the placement of the decapper/expander in the die -- my set of .375 H&H dies has a decapper/expander stem that's so far off that it doesn't even come close to center -- maybe .1" off at best.

I called Redding about it and the tech there said they've tested and found it doesn't make a difference in accuracy. I was skeptical but as soon as I got a Casemaster I checked and found that brass sized in that die was absolutely the dead-straightest I had.

I haven't experimented but doubt that the location of the brass in the shellholder could matter much -- when the ram goes up the die is going to move the brass where it wants it anyway.

John Barsness suggests sizing with the expander out and then replacing it, pushing it in just far enough to do the neck. For some reason he says it comes out straighter. Check out his piece "Factors in Accuracy" -- available over on 24hourcampfire.com. Personally I'd just buy a couple more decapper/expanders and see which ones worked better.

Really I'd suspect neck wall thickness most.

John

The runout on the bullet is greater than the case neck runout because of simple mathematics: The angle of error opens wider and wider the farther you get from the case mouth.

The good news is that with larger caliber, heavy bullets like the .35's, a given amount of runout affects the bullet's POI less than it would if that same amount of runout were exhibited on a 22 caliber bullet.

It seems that in your situation, the case neck thickness is off. The RCBS Casemaster has the ability to measure case mouth thickness, but it's tricky to set up. The technique I described to correct case mouth runout won't fix runout if the brass has uneven case mouth thickness. But it does seem to work when runout is caused by varying rim thickness on the case...

If small increments of runout affect the groups at long range, it would have to be by the very slight velocity differences caused by the runout. By the time the bullet has reached the 300 yard point, all "yaw" or "wobble" induced by the runout is stabilized. But the velocity of the bullet will have been altered by it's less than stable flight from 0 to 300 yards, and it seems very plausible that barrel time would also be affected by runout (the bullet engages the rifling crooked, and leaves the muzzle slightly later in the harmonic whip cycle. It may also be slightly slower, but with a .5 to 1 percent error rate on even the best chronographs, this might be impossible to measure for us common folk).

You don't mention the brass you're using, but with the uneven case necks you mention, I would hazard a guess that it is Remington brass. Winchester cases are normally better in this department, though Remington has its good lots, and Winchester has its bad...

Take care,

Dan

TXPO==Don't worry so much about runnout. A good load in a good gun with a good barrel will shoot just GREAT. Load 10 rounds of ammo with your dies. Run the loaded rounds over your casemaster.
Take the worst 4 and put into a group and take the best 4 and go to the range. Then tell us your results. Take your caliper and grab a sheet of paper out of your printer and measure the thickness. It will be about .003". NOW THINK ABOUT IT. Some of the ammo has a total wobble up and down of .003"--the thickness of that computer paper. My goodness--the average hunting rifle has a loose chamber and even if your ammo was perfectly straight it couldn't be held perfectly in line with the barrel cause it sits "low" in the chamber. When that bullet slams into the rifling at thousands of psi it gets the crap beat out of it--a few thousands of an inch will MAKE NO DIFFERENCE. pLUS IT NOW GOES DOWN THE BARREL.
Imperfections in the average hunting barrel will now have far more effect than that very little wobble. And the vibration of the barrel will make or break your accuracy as the bullet exits the barrel.
Having straight ammo certainly can't hurt but in my book it adds about 2% to the overall accuracy equation ---other variables will have far more impact.

Kraky,

I'm with you on the .003 to .004 thousandths runout on a 30 caliber bullet won't be a major (or even noticeable) problem. I think I'd draw the line at about .0025" with a 1/4 MOA 22 caliber varminter.

Here is a link of an exchange I had with a fellow shooter on another board. About half way down the page we begin discussing why his groups are larger (MOA-wise) at 100 yards than at 300 yards. He discovers that, as I suggested, his loaded rounds had a high level of runout (.010" I believe).

http://216.219.200.59/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=17&t=000015

And here is another link where the same principle is demonstrated. In neither case was the issue a bullet stabilization problem, but rather a runout induced "yaw" that took a couple hundred yards to stabilize...

http://216.219.200.59/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=13&t=000272

In this second case, the rounds in question were .308 win rounds with heavy bullet, exhibiting about .007" of runout.

Dan Newberry
green 788

This is a great thread on run out, but I don't think that's TXPO's problem. Even .007" runout isn't going to open groups from 3/4" to 3". With regards to that group size, I would look at the scope, base/rings and action bedding/screws.

Now, getting back to run out.....

I just got off the phone with Sierra and they have my head spinning. I was told that even .001" of runout measured way out on where the ogive of the bullet starts will affect accuracy at ranges over 200 yds!

I was advised to square up the sizing and seating die with the ram before setting the lock ring.

Which one of the techs told you this?

Runout induces a "yaw" or "wobble" initially, but the effects of this go away as the bullet stabilizes.

Runout serious enough to affect velocity will have an effect on group size way out yonder, but I doubt that would be all that easy to measure.

I think .001" at the tip of the bullet is extremely good... You should have mentioned to the Sierra tech that their own match bullets often have that much runout at the tip--as evidenced by the fact that long range benchrest shooters cull the best Matchkings for the 1K shoots...

That newest Sierra tech doesn't seem to be the sharpest tool in the shed... I forget what his name is...

Dan

Re groups at 100 yds verses 300 yds and what effect runnout might have........... I have a 300wby. I neck turned a batch of brass and after fiddling a little on my forester dies can reload this stuff with .001" runnout. My favorite hunting load in that gun is a barnes 180xbt at 3250 fps. BUT I almost never discovered this load. It shot 1.5-1.75" 100 yd groups. I almost wrote the load combo off because anything that bad at 100 yds would be terrible at 300 yds right? But at 300 yds it will shoot 3" groups. (I am talking nice round groups so my bullets are landing about 1.5" away from my crosshairs center and that's about as good as I can shoot with a 10 power heavy reticle scope.) Now I realize this gun has freebore so maybe my virtual zero runnout is getting kitty whampus going through the freebore. BUT, I would attribute it more to that super long bullet doing a little wobbling and then settling down. It's just one of those shooting gremlins.

If you want to add another gremlin to chase you can think about the quality of the bullet and articles written on the juhnke (I think I spelled it right) machine. This thing sorts bullets by concentricity of the bullet. The theory which seems pretty well proven is alot of flyers are caused by imperfectly made bullets. Which to me is more plausible than a tiny bit of runnout.

Kraky,

Your experience with the 300 Wby is further confirmation that runout affects the close groups more than the downrange groups.

A bullet with "yaw" or "wobble" will deviate from the inertial line imparted by the barrel, up until it stabilizes. It then begins tracking straight, but just a bit beside the interial line. Sort of like a curve ball when the pitcher throws it. After it stabilizes, it follows its inertial tendency...

The 50 BMG does this. Its 100 to 300 yard groups are pretty bad, but a good one can drill a 10" plate at 1200 yards without much trouble.

I agree with you that runout has to reach a certain level before any ill effects can be noticed.

I have read parts of, and heard much said about the NRA highpower study that was done several years ago that seemed to indicate that runout affected long range groups more than close groups. I must admit that I don't believe this study to bear out reality. It is possible that the quality of the bullets and other components available when that study was conducted made it impossible to draw a cogent conclusion.

Dan

I think you guys have way to much time on your hands and need to get a job....runout on hunting loads is just funny and the result of over active imaginations....All my hunting rifles shoot under and inch or near that...with just plain handloads..and if your getting 3/4 one time and 3" another with the same you need to look at either your shooting style or perhaps your barrell is full of copper...run out will change little and is only applicable to bench shooting, as are many of the handloading techniques we use today....My experience is a rifle will shoot or it won't and if it won't get rid of it...

I think you guys are correct, that the 3" groups are not a result of high runout (although, if it is bad enough, yes--it will create 3" groups where a 1" group would have been). The higher the degree of runout, the greater the deformation to the bullet when it slams into the rifling crooked.

Likely, though, the problem is--as some of you say--something else... Sighting, bedding, whatever.

Since the thread opened with thoughts on runout, and the measurement of runout, it sort of spawned the rest of all this.

Runout isn't unimportant. I have a 1972 30-06 Remington ADL (glass bedded, free floated) which is "groundhog accurate" to 400 yards. It shoots `1/2 MOA and better 100 yard groups with my best handload--provided the runout numbers are kept under .004"...

Three shot groups from my Savage 10FP in .308 win more than double in size at 100 yards (1/4" to 3/4") if runout exceeds .004" or so.

Dan

Dan,

The Sierra tech is Caroll #7.

The topic was on oversizing of necks with factory dies vrs special dies such as Reddings Bushing Dies and the fallout from oversizing such as runout. I have some match ammo here that has done proud for me and it's runout is .002". This is a 6MM Rem Intl. used at 200 yds. Ignorance was bliss until I got the RCBS Case Master.

Ray,

The rifle in question is a new .220 Swift barrel on a varmint rifle with a glassed in stock. This rifle is expected to shoot very well as the requirements are higher than for a game gun. Thus the extra efforts. It does seem rather anal however. But when I miss it's really my fault no matter what.

Caroll is one of the senior Sierra techs... The boss, if I'm not mistaken. I don't know what to make of his statement, but I'll give it some thought and ask him next time I speak with him.

He's a good guy--he's given me a lot of bullets for testing, and he gave the www.snipershide.com rifle project "Ghostdancer" several boxes of 142 SMK's, and agreed to sponsor the riflemen...

Hmmm...

Anyway, good luck with the Swift. That's one rifle chambering I have no experience with, but plan to very soon...

What is the twist of the barrel you're using?

Dan

Kraky and others...

What do you think about the "squaring the dies" issue when using the Forster Co-Ax. I figure there's enough play in the cross bolt system to allow the die to "float" and square itself up??? Maybe just wishful thinking on my part?

R

In the Forster Coax the need to square the dies doesn't exist. It's particularly so when you use their pinch bolt lock nuts. The pinch bolt arrangement used by Hornady and Forster square the dies to the lock nut which in turn floats in the squared boss. This mostly eliminates the problem of the nuts that lock on the die threads, from other manufacturers. When the die is set up originally I size a case on the coax and check its concentricity. A time or two I've had to reverse the lock nut to achieve a concentric sizing, I suppose because of some miss-mating of the surfaces of the threads.

The same "floating" arrangement can be achieved in a standard press with the use of a rubber O ring as comes with Lee dies, inserting it between the lock nut and the press, however that takes a bit more adjustment and must be done each and every time you use the die. In the coax you just slide the already set up die into the boss and go to work!

An O ring on the expander can also effectively reduce the problem of the expander pulling the neck out of round by allowing it to float some. A proper expander size and lubing the inside of the neck, and/or the use of a carbide expander, greatly reduces that problem. Use of bushing dies totally eliminates it. I've never used this as I believe the unsupported case floats or moves a bit in a shell holder at the time the neck is being extracted over the expander.