I have read somewhere that you can remove the last couple inches of rifling in a barrel to help with pre stabilizing of the bullet prior to leaving the barrel. Have I misunderstood what I was reading or is this a valid process to allow the bullet to settle before leaving the barrel.

The only time I see this is on old military rifles that have oval bores from excessive cleaning.

Not sure what you mean by "pre stabilize". If you required a specific amount to do that and you removed it, what would happen.

Basically a bullet requires only one full turn in the required distance, twist rate like 1 turn in 12", to be fully stabilized, any more is basically just icing on the cake so to speak. The bullet starts stabilizing the instant it begins to be rotated by the rifling.

I'm certain there are copious studies relating to stabilizing found by searching the net that will give you a better feeling for what's going on.

Basically the muzzles of rifles get dinged up in many ways...cleaning, riding on the floor of vehicles, poking things with the muzzle, hitting hard objects, dropping it and just plain muzzle blast from hot gasses hitting the base of the bullet as it exits and reflecting backwards etching the edges of the rifling, etc.

Cutting off a half inch or slightly more tends to result in sharper rifling or removal of dings and gouges and restoring accuracy.

Many times just re-crowning with a brass round headed screw and valve lapping compound will remove/restore those lands and groove edges.

I cut 2 inches off a 95 Mauser that was key holing at 50 yards.

The front inch or so was badly worn now she well place them into one hole.

I guess one could do the same with boring the barrel out but it was easier to cut it off and re crown.

Jeezzzz...I totally missed that "boring" bit.

Short answer is MAYBE and P dog's answer is closer to what is actually done...you can do it with a hack saw, then use the crowning tools from Brownells to finish the job.

I've done several "new" barrels that you could actually see the bad crown...chucked the square cutting tool in a drill motor, set the speed down low, used lots of cutting oil INSIDE the bore and on the cutting face and a light, steady pressure and chewed away until the muzzle was square...then used the 45° cutter to finish off. Be careful not to get the tool chattering

MUCH easier than taking a rifle apart and chucking up in the lathe and does as good a job.

Once you get past the bluing you can see any out-of-roundness very easily. Just keep cutting back 1/2" at a time until no out of roundness(hopefully) is apparent but no more than about 3". If it is still wobbled out by then the barrel probably came that way. You can see any wobble by looking up the bore from both ends usually.

"Backboring" can also lead to INSTABILITY as the gasses blow out around the bullet and any irregularities in the boring squareness or the bullet base squareness can cause gas turbulence that will upset the bullets exit.

Pre stabilizing? Never heard of it; please cite a reference/article/book, etc. Otherwise, consider it internet nonsense, of which it is full.
Bullets have to leave the barrel, spinning, cleanly. Anything that disrupts that is bad.

quote:

Originally posted by dpcd:
Pre stabilizing? Never heard of it; please cite a reference/article/book, etc. Otherwise, consider it internet nonsense, of which it is full.
Bullets have to leave the barrel, spinning, cleanly. Anything that disrupts that is bad.

+1

+2

Les Bauer is doing this to a 30" barrel for bench rest shooting. Some people refer to it as a noodle. As far as a book reference That is why I'm asking if anybody has heard of this. I can't remember where I heard of it first.

OK; call and ask them.

Very interesting.

I have a 6.5X54MS carbine (Greek military conversion) that used to shoot ok. I tried to polish the dark bore and now it shoot dinner plate groups at 25 meters with the odd key hole!

I was wondering if the Bored out an inch of the muzzle end, it would shoot better.

That's Les BAER...No "U"...Check out Bill Calfee and Benchrest Central...there is some talk concerning "integral tuning"...totally new to me!!!

Come to think of it...all my integral brakes have a "back-bored" section slightly longer than the length of the ports and have an Id larger than ...and all my removable brakes have an "expansion section" usually the same size as the thread minor dia. ending about a quarter inch from the end of the brake. The exit hole is roughly 30 to 40 thou larger than bullet size.

These "back bored" sections don't seem to cause any problems with "instability"...I need to think this through a little more...all that stuff I said earlier might just be that..."stuff"...but I did believe it was true at that point.

There is ALWAYS new things being developed and old truisms are getting re-evaluated constantly...TOTALY NEAT ISN'T IT.

James Pappas manufactures a parallel noodle for rimfire.
This is my parallel noodle screwed on my Shadetree Eng. tuner on my BR rifle. Never spent time with it as it made my rifle overweight.

quote:

Originally posted by NONAGONAGIN:
That's Les BAER...No "U"...Check out Bill Calfee and Benchrest Central...there is some talk concerning "integral tuning"...totally new to me!!!

Come to think of it...all my integral brakes have a "back-bored" section slightly longer than the length of the ports and have an Id larger than ...and all my removable brakes have an "expansion section" usually the same size as the thread minor dia. ending about a quarter inch from the end of the brake. The exit hole is roughly 30 to 40 thou larger than bullet size.

These "back bored" sections don't seem to cause any problems with "instability"...I need to think this through a little more...all that stuff I said earlier might just be that..."stuff"...but I did believe it was true at that point.

There is ALWAYS new things being developed and old truisms are getting re-evaluated constantly...TOTALY NEAT ISN'T IT.

Bill Calfee, I don't think so!

quote:

Originally posted by NONAGONAGIN:
That's Les BAER...No "U"...Check out Bill Calfee and Benchrest Central...there is some talk concerning "integral tuning"...totally new to me!!!

Come to think of it...all my integral brakes have a "back-bored" section slightly longer than the length of the ports and have an Id larger than ...and all my removable brakes have an "expansion section" usually the same size as the thread minor dia. ending about a quarter inch from the end of the brake. The exit hole is roughly 30 to 40 thou larger than bullet size.

These "back bored" sections don't seem to cause any problems with "instability"...I need to think this through a little more...all that stuff I said earlier might just be that..."stuff"...but I did believe it was true at that point.

There is ALWAYS new things being developed and old truisms are getting re-evaluated constantly...TOTALY NEAT ISN'T IT.

What Calfee does with integral barrel tuners is about barrel vibrations and not bullet stability. From what I understand, his goal is to minimize vertical dispersion from shot to shot due to velocity variations in .22lr ammo by creating a "parallel node" in the vibrations where the barrel muzzle is in the same spot and in a flat position when the bullet exits the barrel rather than whipping up or down.

Of course, your tuning theories may vary...

quote:

Originally posted by butchlambert:
James Pappas manufactures a parallel noodle for rimfire.
This is my parallel noodle screwed on my Shadetree Eng. tuner on my BR rifle. Never spent time with it as it made my rifle overweight.

Here's a noodle on a .22lr benchrest rifle, in slow motion:

http://www.youtube.com/watch?v=M0U_d9IhaMc

I'm surprised the vibrations are that noticeable. Also, all the gases exit out the end and not the port holes. I've tried one on my Suhl 150 and it didn't seem to shoot any better than with my lightweight Harrel tuner, but I didn't try messing with it much.

Those devices have nothing to do with "removing the last couple inches of rifling" as the OP asked about. These things affect/adjust barrel harmonics.
I still say that the rifling removal idea is invalid until I see otherwise.

As far as I recall, bullets yaw a little as they leave the barrel and then "go to sleep" some distance down range. Does this back-bore have anything to do with that condition?

I have NO idea what this "thing" is or might be..."pre-stabilizing" has many inferences/connotations/descriptions' and that "noodle" thingy looks like an extended brake, the additional weight will certainly change the barrel harmonics. I've never competed with rim fires so it is of slight academic interest to me what is going on in that world today. Harrell's Precision sells a neat looking "tuner/brake" which is also new to me since I haven't visited or bought anything from him for several years.

I did some testing on barrel vibrations way, WAY back by nipping off a quarter inch of barrel or so, after reading about it somewhere. The test was crude to say the most...it did SOMETHING, BUT, along with this testing I also found out that by changing the bullet seating depth, powder brand/type/amounts, bullet style/type, primer brisance, bench rest prepping brass, or even case brands I could achieve groups from 1 1/2" to bug holes...so now I leave the "barrel tuners" off for center fire...rim fire has an additional set of problems and barrel tuning seems to be a valid way to increase accuracy.

Very few believe or want to bother doing these types of experiments much less wanting to develop accurate loads...a lot of people with blinders on out there and many of then DON'T REQUIRE high levels of accuracy to begin with...so why bother...it's a valid point in my book.

As I said before, "things change" ...this "whatever it is" might be something new Les is working that hasn't hit the mainstream "rumor mill" yet on or might be a mis-read/mis-understanding on the part of the OP and/or absolutely nothing...who knows at this point. I have a very open mind and don't dismiss, out-of-hand" things I read online or in the publications I peruse...many times I argue for/against something but that is more in the realm of getting more information.

Maybe someone will actually contact Les Baer to get the real info and report back...until then it remains a possibility and a mystery to me, and No, I won't bother Les, in this case, unless I were buying something from him.

I amnot a trained gunsmith or even in that trade. Since I retired the navy I have plenty of time to think on these kind of things. Once I get my lathe in my shop maybe I'll bore out the end of the original barrel and see what happens as I plan to buy a green mountain 20" barrel. As far as the Les Baer thing I was sent an article about a 30" bench rest barrel he has developed in 556. Prestablization is a term I used for lack of better words. The ideal is all about allow the bullet to settle after leaving the rifling and before actually leaving the barrel. A long distant shooter who's last name was Parson did this to some of his rifles. I'm just playing around with 22lr as it is cheap and with the SR22 I can change the barrels and parts pretty cheaply. I do appreciate the input I'm getting. Triggertate that is exactly what it is suppose to do. I just don't know if it will.

I have back bored a couple BR barrels. I did not trust a short stiff solid carbide boring bar over 1.5" deep and it ain't easy getting a good crown that far in. Yeah I know, I could go in with an endmill or some type of tool to touch it up.

Anyway, I saw no difference on the groups. Not saying that it doesn't work, just not for me.

Couldn't you have used a brass rod faced to have a 11 degree face and lapping compound to polish the crown?

Well, anything might work, but I'm thinking that ain't good enough for BR. What is magic about 11 degree?

quote:

Originally posted by mdvjrp93:
Couldn't you have used a brass rod faced to have a 11 degree face and lapping compound to polish the crown?

quote:

Originally posted by NONAGONAGIN:
I have NO idea what this "thing" is or might be..."pre-stabilizing" has many inferences/connotations/descriptions' and that "noodle" thingy looks like an extended brake, the additional weight will certainly change the barrel harmonics. I've never competed with rim fires so it is of slight academic interest to me what is going on in that world today. Harrell's Precision sells a neat looking "tuner/brake" which is also new to me since I haven't visited or bought anything from him for several years.

I did some testing on barrel vibrations way, WAY back by nipping off a quarter inch of barrel or so, after reading about it somewhere. The test was crude to say the most...it did SOMETHING, BUT, along with this testing I also found out that by changing the bullet seating depth, powder brand/type/amounts, bullet style/type, primer brisance, bench rest prepping brass, or even case brands I could achieve groups from 1 1/2" to bug holes...so now I leave the "barrel tuners" off for center fire...rim fire has an additional set of problems and barrel tuning seems to be a valid way to increase accuracy.

Very few believe or want to bother doing these types of experiments much less wanting to develop accurate loads...a lot of people with blinders on out there and many of then DON'T REQUIRE high levels of accuracy to begin with...so why bother...it's a valid point in my book.

As I said before, "things change" ...this "whatever it is" might be something new Les is working that hasn't hit the mainstream "rumor mill" yet on or might be a mis-read/mis-understanding on the part of the OP and/or absolutely nothing...who knows at this point. I have a very open mind and don't dismiss, out-of-hand" things I read online or in the publications I peruse...many times I argue for/against something but that is more in the realm of getting more information.

Maybe someone will actually contact Les Baer to get the real info and report back...until then it remains a possibility and a mystery to me, and No, I won't bother Les, in this case, unless I were buying something from him.

You know a lot of BR people have done what you have suggested and much more. I didn't post this to say your findings are not valid, only to say a lot of folks have done this.
What has neck tension and seating depth told you?

Many years ago, I read a paper by one of Winchester's ballisticians wherein he claimed a recess at the muzzle which was twice the bullet diameter and (I think) three calibers deep would reduce intial yaw. I have no reason to doubt this but also have no reason to believe it! I have been pretty satisfied with my target rifles the way they are and haven't felt that inital bullet yaw was affecting my performance all that much. I can usually count on my own ineptitude to do that for me! Regards, Bill

Unless I'm mistaken (that could be a real possibility) 11 degress is used for target crown. The people on this sight has so much knowledge it is un real. The only draw back is you really don't know who you are talking to that can give you a little pause when taking them at their word.

You don't have to take my word, but I believe 90% of BR shooters cut their crown 90deg from the bore or just a flat crown. The 11 degree thing was abandoned many years ago.

A long discussion on counterboring a crown.
http://www.usrifleteams.com/lr....php?showtopic=15814
On a new barrel I think it a solution in search of a problem but for a barrel with muzzle wear it can extend life.

OK thanks Butch I did't know that. Just a novice at this so all info is appreciated.

I ain't never had a barrel with muzzle wear. I have had a bunch with throat wear.

Ahhhhh...neck tension and seating, Butch...I tried to come up with uniform methods to measure both seating and "pull"...pre digital scale age...nothing I did was uniform enough to be of any valid use...didn't have the correct tools...and with todays micrometer seaters you don't have to futz around marking and scratching indicator marks and copying Wilson's fine seaters to get 0.001" seating increments which we all know is REALLY TOTAL BS, unless you also measure and separate bullets by OGIVE lengths.

Basically all I did was to turn necks uniformly to various thicknesses in 0.002" increments and shoot groups then compare. If the neck wall isn't uniform in thickness, the pull won't be uniform and if the inside of the case neck isn't uniform in smoothness then the pull can't be uniform either...this can get very circular and grow into a gigantic hoo-haw when folks get to arguing, but not on the same page...this sport used to be like Golf, gentlemanly...now they're both about money. The LAST BR match I went to ended up the competitors, judges and bystanders in a roundy-roundy...I left my little tin pot and BR AND all other shooting competition...where's the fun???

I started with a load and cases that produced as small a group as possible...mostly 223 and 308 using know loads or one I already worked up...all cases benchrest prepped...I don't waste ammo so 4 shot groups sufficed and I played with statistics for the numbers. I also did a few tests with 22-243, 6mm-284 and 7mm mag...all rifles shot in the 4's with specific loads...not BR but excellent hunters/varminters.

Basically the data indicated that once you found a bug hole group, depending on the cal and powder amounts, as long as you trimmed and cleaned the primer pockets and watched the neck thickness the groups would stay small for a certain number of shots, but NO specific number for cal or case size and depended mostly on the pressure and amount of throat erosion being produced. Those hot rock would chew up a throat in a NY minute and would require seating out by a certain amount...again depending on many factors...0.005-007" sometimes more...all that cam be measured easily enough.

In the old days I could burn out a throat in one shooting session of 500 rounds with a 22-250 when the ratz were thick...literally burning up a barrel...you can guess how many ratz I hit toward the end.

Every time you cycle a round, the case gets pressure reshaped...brass flows, usually from base to neck depending on how much you resize and how well your sizer fits the chamber and how well the resized case fits the camber...and the case stretches.

The amount of tension also depends on the type/brand of brass and the wall thickness. As I thinned the necks the groups did change and I could regain a bughole by slightly changing the seating depth, the bullet length, powder type, using a tuning screw...SOMTIMES...it's basically about harmonicas and vibrations.

I've zapped a lot of brass, more than a couple of barrels doing all the testing I've done, got some very useful info but think the cost was worth it.

The rifle itself and the shooter has to be capable of showing any changes and if not the changes get lost in the noise. With todays technology just about any rifle can be capable of delineating small changes associated with any well thought-out test situation.

Basically the same thing with seating...each cal seems to have a starting place to get to the highest level of accuracy with the least amount of effort. My 17 20 and 22 cals seem to like it off the lands in the ~0.020" range and the larger you go the closer to the lands you need to be...BUT...that also depends on the type and construction of the bullet, the lead design, throat depth...etc, etc, etc.

The MAJOR problem in getting a bugholer is each rifle is different in stock type, design, use, and all the myriad variations there are...and people being people...many would rather fight over miniscule, useless BS with total NON-understanding than actually spend some time working out what THEIR RIFLE is telling them from their targets and woe be to the person that disagrees and is trying to pass on valuable information...again...people tend to defend a position rather than sit back and think it over.

FWIW...Anyone interested in the "Back boring" can goggle "Back boring a rifle"...there IS some information on it, both as a protection strategy and velocity reducer.

I like a 45° or 60° crown with about a 3/8" deep "back bored" section for my hunting shooters...I never called it that, it was just a way to protect the muzzle, but I've done a lot of target rifles with 11° and flat crowns...they all shoot and if they don't it's NOT the crown.

I still use this information to produce my ammo but now I'm not as anal...a 1/2" rifle is all I require now...a quarter incher is just TOO much of a PITA to do.

Basically...I think it's just about how anal you happen to be and what you use the rifle for as to which crown you want/need.

Clowdis...a solution in search of a problem is one way to advance, to find answers...a wrong answer is just as effective a learning tool as a correct one...scientist test hypotheses to arrive at a correct solution.

Every bit of this information is now available somewhere online...nothing is cast in stone...you either "get it", understand how to use it, deny it or don't need it.

No Flame or Diss intended or implied...sorry for any rants also, I'm going nutz waiting for my new toy...weather is lousy, snowed yesterday...nothing to kill...shot up all the pine cones in the back yard and have to reload my 458 American, 357 H&N, 416 Taylor and 45 auto now ...have to vent. hahahahaha

Wow I never expected this to go so deep. But it has been educational. A lot to think about and to apply the best I can.:-)

NONAGONAGIN

What have you learned about the effect of neck tension and seating depth? How do each of these things affect the bullet?

I do spend a lot of time(or I used too)working with my BR rifles.
On my custom hunting rifles I take very little time with them tuning their loads. If they shoot below 1MOA with either a fouled or clean bore, it will kill what I hunt. I know a lot of people spend a lot of time at the range wringing out a rifle to get the ultimate result. I'm happy for them. To me a rifle is a tool.

quote:

I do spend a lot of time(or I used too)working with my BR rifles. On my custom hunting rifles I take very little time with them tuning their loads. If they shoot below 1MOA with either a fouled or clean bore, it will kill what I hunt. I know a lot of people spend a lot of time at the range wringing out a rifle to get the ultimate result. I'm happy for them. To me a rifle is a tool.

For years I spent hundreds of hours and $$ working to get my pencil thin hunting rifle to shoot sub MOA groups. Then decided to spend that time on my BR and if the hunting rifle would do MOA each and every time it was a winner.

For those of you that want to spend the time to try and get your hunting rifle to shoot like a BR then by all means go for it. I have other things I'd rather do now days.

Yeah...each rifle has a different purpose and accuracy potential/actual need and each shooter has the same.

My original premise is/was the more accurate the rifle and shooter, the better able to make a quick kill and the less the hiccup/bad shot potential got in the way.

Gets a bit anal/picky/costly. To get a rifle/ammo to 90% accuracy potential, 1" to 1/2", is relatively easy, quick and cheap...to get that last 10%, 1 cal bughole, gets into that tedious, TOTALLY anal with minutia, time consuming, mega bucks realm.

My time is almost up, why waste it futzing around on accuracy levels that are not required...except for varminting ...those little critters are hard to hit beyond 50 yds with a 1" rifle.

BR???? That's so far in the past I'm not exactly sure what BR means anymore.

I've heard that 1" story and it's the man not the tool before...many times...but I've never seen a 1" rifle win a BR match...maybe a Service rifle match. AND...I've never seen a mechanic build a race car engine with junk tools ...but it's a good laugh anyway. hahahahahahahah