BURN MARKS

[GLShooter]

Last PM I got a post from here that has a broken link or was withdrawn. It had a picture of a target with some whispy marks with the bullet holes. The fellow also said he had a couple tumblers. He was shooting a 25 VMAX out of a 17 FB with a 9 twist.

I have had this happen and what it is the jacket is starting t0 rupture and that is lead bleeding out. The next thing is it blows up in some cases. This a 50 grain VMAX at 3700 out of an 8 twist 22X6.8. I fired 100 rounds that day and ended up with 97 holes on target. The ladder started at about 3600 and went up. The faster it went I started seeing these and then eventually they just had a cloud of smoke between me and the target. I had a PD hunt coming up so I loaded this load up as I had no time to work on anything else for this new tube. When I hit a dog it was the most explosive thing I've ever seen in the field. Shot one adult and killed its partner and three pups on the same mound!! I've shot a lot of doubels and t he odd triple but nothing like this.

Here is the "comet tail" out of one of those VMAX.



BTW the groups were in the 4's shooting this one. I switched to Sierras and Noslers after this and all is well in Whoville. I have 22 NXS 1:8 done on the HAGAR that will exceed the 22X6.8. I found that at 3775 I could blow up 1 out of for of these. Once again a switch to Noslers holds together at 4,000.

Greg

 

[CJ6]

Looks like the jacket is starting to fail.

 

[GLShooter]

Looks like the jacket is starting to fail.

That's what I said..(VBG)

 

[6bra1k]

sorry it is lead in the core melting and comming out the NOSE the swirl is bullets spin
likely to fast or too small a bore...friction heating and boiling some of the lead core

 

[GLShooter]

Fast twist and speed combined no doubt. You may well be right on that. I do know that some are not reaching the target at 100 yards.

Greg

 

[Rsadams]

Slow them down and retest... To much speed and way to fast a twist....

 

[GLShooter]

Slow them down and retest... To much speed and way to fast a twist....

I know how to fix it but I just changed to a structurally stronger bullet m the magic number on that VMAX is 3450. At 3500 things start their issue. At 3600 it gets pretty Western.. I'm shooting small bore wildcats in the AR and speed with great accuracy is showing up a great deal so Nosler and Sierra get the call. My barrels tend to the fast twist so I had o deal with that over the past decade or two.

 

[jelenko]

3700 out of an 8 twist

That's producing 333,000 rpms. At least for Hornady's 75's, Horndady said their max rpm is 280,000 and Sierra said their max for 77 SMK's was 250,000 - 260,000 rpms. [I had called both about bullets not showing up on paper at 100 yards].

 

[Tesoro]

sorry it is lead in the core melting and comming out the NOSE the swirl is bullets spin
likely to fast or too small a bore...friction heating and boiling some of the lead core

seems to me like that bullet would be sinning ccw to leave that splatter mark?

 

[GLShooter]

That's producing 333,000 rpms. At least for Hornady's 75's, Horndady said their max rpm is 280,000 and Sierra said their max for 77 SMK's was 250,000 - 260,000 rpms. [I had called both about bullets not showing up on paper at 100 yards].

Yep. And if you want to really see something fast the 20-243 really spins em. These hot 22s shine with the 60s on up. I need to try some of the lead free pills.

 

[STS]

sorry it is lead in the core melting and comming out the NOSE the swirl is bullets spin
likely to fast or too small a bore...friction heating and boiling some of the lead core

If that's the case how would you explain a barrel/bullet combo that was shot its entire life at the same velocity and twist rate and comet tails showing up only in the last 400 rounds? I've shot 2 .17 Mach IV barrels off one of my rifles and both did the exact same thing at the same round count. Both lasted a little over 4000 rounds and started exhibiting this behavior at around 3600 rounds. Same 10 twist at 3850 fps with a 25 grain hp. I'll step out on a limb and suggest it's the erosion of the first 2 inches of the bore that damages the jacket and the resulting fracture is where the lead is escaping. It does leave some really nice "smoke trails" on the way to the target.

 

[GLShooter]

I think you are on to a potential possibility in your case. My barrels are doing this brand new. I only posted this for documentation the other guy.. I'm well aware how to fix it.

These boards are great for generating use of the gray matter.

Greg

 

[6bra1k]

If that's the case how would you explain a barrel/bullet combo that was shot its entire life at the same velocity and twist rate and comet tails showing up only in the last 400 rounds? I've shot 2 .17 Mach IV barrels off one of my rifles and both did the exact same thing at the same round count. Both lasted a little over 4000 rounds and started exhibiting this behavior at around 3600 rounds. Same 10 twist at 3850 fps with a 25 grain hp. I'll step out on a limb and suggest it's the erosion of the first 2 inches of the bore that damages the jacket and the resulting fracture is where the lead is escaping. It does leave some really nice "smoke trails" on the way to the target.

it was documented several years back....classic tip squirt
so your old bbl has the same smooth surface same heat as when it was new ...not things change with wear
but you are entitled to your opinion...\

slow it down and see

 

[6bra1k]

Fast twist and speed combined no doubt. You may well be right on that. I do know that some are not reaching the target at 100 yards.

Greg

because they lost so much lead they aint the same bullet anymore...or you are just plain blowing them up

 

[Timberyote]

You need more distance from the target. 5 yards isn't cutting it!

 

[STS]

it was documented several years back....classic tip squirt
so your old bbl has the same smooth surface same heat as when it was new ...not things change with wear
but you are entitled to your opinion...\

slow it down and see

No offense intended, but you don't seem to have worn out enough barrels to have seen bullet damage due to wear in the first couple of inches. I've had several .22-250, .22BR, .22-250 AI and a few others that have all done the same thing in the final stages of their life. I have cut off and rechambered barrels that had a long enough shank, and it stops the damage and bullet issues..... for a couple thousand rounds. Until it burns out again then it's the same scenario all over again. This isn't an opinion, its been known and repeated over and over again for the 50+ years that I've been aware of it. Burned up, heat cracked barrels will produce targets exactly like the one exhibited above.

 

[6bra1k]

No offense intended, but you don't seem to have worn out enough barrels to have seen bullet damage due to wear in the first couple of inches. I've had several .22-250, .22BR, .22-250 AI and a few others that have all done the same thing in the final stages of their life. I have cut off and rechambered barrels that had a long enough shank, and it stops the damage and bullet issues..... for a couple thousand rounds. Until it burns out again then it's the same scenario all over again. This isn't an opinion, its been known and repeated over and over again for the 50+ years that I've been aware of it. Burned up, heat cracked barrels will produce targets exactly like the one exhibited above.

yes...the damage is HEATING UP THE BULLET CAUSING THE SQUIRT.
i am 73 i may have seen a worn out bbl or two in my time.
i have a lathe, i have chambered a few in my time
i have seen the first hand....sam bbl same load all the sudden a problem....HEAT FROM DAMAGE

 

[STS]

Couldn't possibly be from the barrel being a couple thousandths over bullet diameter could it? Nah, no way that could be the problem.

 

[6bra1k]

Couldn't possibly be from the barrel being a couple thousandths over bullet diameter could it? Nah, no way that could be the problem.

no it would not....the distinct trail center out is from the nose

 

[STS]

The lead boils out of the nose?