bullet blowup???

[mrjdasr]

shot two 1000 yd matches [f class] on sunday. unlimited sighters
20 shots for record first match went fine cooled barrel with wet towel till cool to the touch started second match only used three sighters shot 10s & x's till the 18th shot 3 18 went haywire
& scored a 7 on the extreme left hand side # 19 hit at the very bottom for another 7 after a brief wait # 20 was back in the xring my son was shooting next to me and had the same trouble only his bullets didn't even make it to the target both of us shot matches in June with the same results both guns have krieger 8 twist .236 bore barrels mine is a 243 ai his is a 244 ai
my velocity is 2980 & his is 3060. the bullets are 105 vld's with J4 jackets rather not mention the brand name
any one else having 105's coming apart
any ideas on the cause other than a barrel change, we just bought these from midway les than 600 shots ago

 

[rcw3]

Your choices in relation to your barrel kind of have things stacked closer to the edge in favor of bullet failure:

1. .236" bore that cuts into the jacket more,vs .237" bore)
2. Cut rifled barrel with traditional lands with square corners that cut sharply into the jacket,versus "R" or "C" type lands)
3. Directly opposing lands,vs 5 grooves and lands).

Randy Robinette had some pretty strongly worded info out there suggesting that a barrel with the characteristics like you have is somewhat of a bullet killer for bullets with J4 jackets.

If you are also running plain,vs moly bullets), that's another factor getting you closer to failure.

If you were running Sierras or Lapuas with that setup, no problem.

Robert Whitley

 

[rhino]

I know of three people having "problems" with 6mm J4 VLD's.

1. Mark
2. Robert
3. I forget his name shoots 6mm remington.

So led me to get rid of my .243 LW and just shoot my swede. Robert makes a good point. If I had to the time to screw around I think a Pac-nor 3 groove might be the answer to the problems.

All of the people I have seen and have conversed with shot or shoot at Bodines.

Throw in the fact that the 6mm's don't seem to fair well in the Bodines wind and its a no brainer. If I do stray away from the swede I might have to try Alan's 7 WSM.

RHINOUT!

 

[rcw3]

Its heat in my opinion that is killing your bullets.The tight bore creates more heat due to the added friction.
I know that "Bullet Killer" barrel and the owner of it says its heat.Most bullet makers will try and "Spin Doctor" there way away from the problem buy telling you less velocity will cure the problem.
Take the gun that wasn't making it to the target and shoot 15 shots down it real fast.Now let the next 3 rounds fired sit in the chamber for 2 minutes each and see what happens.
I would guess the first 15 to make it to the target while none of the last 3 would.
Lynn

Lynn

No question heat is part of the equation for bullet failure. When you see that grey puff, it has been suggested to me by a bullet maker that it is melted,or near melted) lead that does that. I was addressing the fact that barrel characteristics can also tend to make the jacket split like a banana peel to expose the core.

Robert Whitley

 

[rcw3]

I know of three people having "problems" with 6mm J4 VLD's.

1. Mark
2. Robert
3. I forget his name shoots 6mm remington.

So led me to get rid of my .243 LW and just shoot my swede. Robert makes a good point. If I had to the time to screw around I think a Pac-nor 3 groove might be the answer to the problems.

All of the people I have seen and have conversed with shot or shoot at Bodines.

Throw in the fact that the 6mm's don't seem to fair well in the Bodines wind and its a no brainer. If I do stray away from the swede I might have to try Alan's 7 WSM.

RHINOUT!

Rhino

I would not suggest I am having a "problem" with J4 jacketed bullets. When I went to Bodines last time, I was there to test out Tubb's new DTAC 117 BN bullets. I lost two of them in mid air for no apparent reason,i.e. only going betweeen 2950-2980 fps). I am fairly certain they do not use J4 jackets.

The night before I happened to think that if the DTAC 117's did not do well I should have a back up load to test out. I made up a WAG Load,i.e. Wild Ass Guess Load) using some very old plain Berger 115's with an estimated powder charge to get them up around 3000 fps. This load had never been shot, chronoed or tested by me at all. When the DTAC 117's did not go well, I tried out the Berger load and had some blow up. I chronoed them a few days after to find out they were going 3050 fps,too fast). These were Bergers I had hanging around for years and were made during the time Spiveco owned Berger and used reclaimed lead for the cores,the reclaimed lead core bullets are much more prone to blow ups). I spoke with Eric Stecker yesterday at Berger, and he says that Carran Precision,the current owner of Berger) no longer uses reclaimed lead for the cores, only virgin lead, and this has stopped a lot of the reported blow up problems. I will be testing some new Berger 115's and we'll see how it goes.

From that perspective I don't consider what was happening as a problem with J4 jacketed bullets.

Robert

 

[mrjdasr]

well, whatever the cause of the failure, a change is called for
i've tried sierra 107 but wasn't impressed also tried lapua 105
scenar don't have any info on the likes and dislikes of either
I use H1000 powder[48.5 grns with 105s] any help with seating depth & velocity for sierra or lapua would be greatly appreciated
thanks for the replies

 

[rcw3]

Lynn

Any ideas on reducing the heat that you indicate leads to bullet blow ups?

Robert Whitley

 

[joesr]

I've had several long discussions with Berger bullets about bullet blow ups.

From their testing and high speed photos what is going on is the core of the bullet becomes liquid and if/when the jacket is thin enough it comes apart.

I'm shooting a 6mm that is yielding 3000 to 3100 fps,105 to 115, all the same) out of a Bartlein and/or Kreiger 4 Grove barrel.

What I know is:

1. the 105 Hornady Amax,I bout to fire form with) blows up about 20% of the time.
2. J4 Jacketed bullets blow up about 30% of the time and some J4 bullets are much worse.
3. Sierra 107 never blow up.
4. DTAC 115's never blow up.

I know the J4 jacked bullet's accuracy is great, but at this velocity, uncoated and in my barrels, they don't stay together.

On the other hand, the 115 DTAC are giving me great accuracy at this velocity as well as no issues with blow ups.

In my opinion you are better to shoot a trusted bullet than one that may at some point not make the target.

Joe H

 

[Rustystud]

6mm 105 blow ups. Recently a top shooter was shooting a 243 at Butner with 105s running about 3150. He had a string of about 10 Xs at 1000 yards and a unexplained miss. He asked for a review and again it was determined he had a miss. About an hour later I was talking to another shooter about 4 or 5 positions over who said he saw a bullet blow up at about the 900 yard line. The top shooter said he did not have bullets blow up. He is a great shooter but naive to think this. Coming from the varmint hunting world I have had bullets blow up numerous times. It happens especially if one is shooting on the edge of maximum velocity and maximum spin. Long barrels also contribute having more surface contact with the bullet. J4 jackets are relatively thin. I think velocities over 3100 fps and rates of twist faster than 8.5 are asking for bullet failures. The accurace node for 105-107s is some where around 3040fps and 3080fps. Groups are good up to around 3150 but fliers become an issue. Consistancy and extreme spread are more important than maximum velocity.

Rustystud