i have a 22-243 that has about 300 rnds through it and now about 2-5 bullets will come apart before reaching the target i talked to someone that said to work the first 6-8" of the bore with j b bore compound and that would help i did but after 30 rounds it does it again even after claning barrel is a brux cut rifled barrel and im shooting 75gr amaxs at about 3550fps 1x8 twist i tried several other bullets and get the same result any of you smart fellows got any ideas on the cause /cure? thanks,Brian
I would guess that your rifling is damageing the jackets. If you were shooting a lighter bullet and a Vmax, I would have guessed that you should shoot a heavier bullet, but the 75 amax should hold up. Are you pushing it to the limit - have you tried a lighter charge? You You shouldn't have wrecked the rifling in 300 rounds unless they were done in two sittings!
do you have access to a bore scope? If the barrel is fairly new, I'd talk to your smith or the barrel manufacturer.
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I used to re-load but now I "hand-load".
-- Well, at least I try --
We've seen this happen with several barrel mfgr's tubes including our own. The combination of high velocity (over 3100 fps), overbore cartridges like the 6x284, 6.5x284, .220 Swift, etc, and fast twist rates for heavier bullets. Combine all of those factors with a bullet with a very thin jacket, and this problem arises. There is just too much stress being put on the bullet by velocity/pressure/rotational stress/teperature. No ONE component is really to blame, but it is the combination of all of them. We have replaced barrels in the past for customers having this problem, and half the time it cures it. Occationally the problem gets worse with no discernable difference in bore/groove dimentions or surface finish of the barrel. Another customer that has a rifle fit by the same gunsmith with the same reamer, same barrel mfgr., sharing ammo, has NO problems whatsoever.
Try shooting a Sierra Matchking bullet in a similar weight and see if the problem persists. The Sierra's, although very accurate, seem to have 'tougher' jackets than many of the other bullets out there. It's rare that we see this issue with Matchkings. It's been long known that you can shoot a 52 gr. Matchking in a .22-250, but try and shoot a 50 gr. "Blitzking" through the same rifle and they come apart! There is sometimes just an operational limit of velocity/pressure for some bullets.
edit: Berger Bullets has done some extensive testing with Mid Tompkins and determined the failure of the 'thin' or regular jacket bullets in the 6.5x284 was due to the amount of friction generated due to the high velocity of these bullets. This friction translates into heat which transfered to the core of the bullet, melts the surface of lead directly under the jacket. This causes a core instability within the bullet and at 250,000+ RPM, the bullet cannot contain the instability and comes apart. Berger is offering a "Thick" jacket version of many of their long range bullets as a result of this testing. Their testing of the "Thick" jacket bullets resulted in no failures in the same rifle, on the same day, with the same load. Hope the info helps!
Brian , I've found that barrels with more lands and grooves , especialy button rifled barrels are not as had on bullets when bushed to warp speeds , I have a Douglas 1-8 on and old 22-250 Ackley that has a few thousand rounds through it , this barrel has always fouled out in 10-20 shots no matter what you did to it its just a rough bore BUT I can run a 50 gr Ballistic tip out at 4300fps with no trouble yet a 3 groove Pac-Nor same twist same reamer and ALOT better bore blows them up at 4000. I personaly think that the 6 grooves in the Douglas combined with shallower lands doesn't tear up the jacket as bad , even though the Pac-Nor is a buttoned barrel.
I have heard the same thing about bullets goin bad in 3 groove Lilja and 4 groove Kreiger barrles.
But like :Kreigerbarrels" said their test show some barrels from the same maker will and some won't.
I'd try a little bit heavier bullet , maybe the 80gr A-max , 77gr or 80gr Match Kings , slow them down a little with the heavier bullet and let the added BC make up the differance. I've also had good luck with 80gr Bergers in the past. and have heard of some guys shooting the 90gr Bergers and 90gr Sierra Match Kings out of 1-8 twsit barrels in hot rods like your and having success , they woulden't stabilize from and of my 22-250's though its worth a try , ask around and see if sombody would lend you a few to test.
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