187 BIB in 13 twist.

[Tony Z]

Today we shot our 1K match where i sat behind aJR of Aus and watched him shoot his second HG card for the day. Now the fifth and eighth shot left a blue smoke burst some fifty yards from the muzzle that didn't continue on with the bullet further downrange, just seemed to jet out a plume and that was it. Now the target returned for a 7.5 inch group and 93.1 score, but two shots were low in the 8 ring at 6 o'clock. Could these be the two smokers? If so, has anyone seen this before from a BIB 187 and what could be the cause? Can it lead to the eventual bullet Bermuda Triangle?
Now i have watched JR shoot these bullets for some years now and this is the very first time i have ever seen anything like this before.
This is a Bartlien barrel in 13 twist @ 32 inches long that is showing great promise and is not long past 400 rounds. Fouling is nothing unusual to any other barrel we have installed before. Cartridge is our usual Redneck, longer neck steeper shouldered 300 Win Mag, and the powder is VV560. Primer is 210 M. Velocity is somewhere over 3200 fps.
Thanks in advance.

Tony Z.

 

[Charles E]

Kinda, sort of, maybe not.

I've had this reported to me, but I can't remember whether it was in HG, which would be BIBS, or LG, which would not. And my HG is a 12-twist. But as I remember, Jeff pushes his loads quite hard, maybe harder than I do. Faster = more friction, more heat.

Also, when it was reported, by Phillip Yott watching me shoot, he said "white puffs." All shots made it on the paper,in the group, so the bullets didn't blow. I think it was atmospherics.

"Blue" or "gray" sounds like lead coming out. I suppose the core can melt some & the bullet still not come apart, but if it melted enough to spew lead, I'd think it would have blown. Where it seems to get hottest is just ahead of the shank/ogive point; at least, that's where they come apart when they blow, by Tooley's tests.

And if enough lead came out to see, I'd think the bullet would miss, rather than being just a touch low.

Still, all pure speculation.

 

[JerryK]

I was speaking with RR to order some 187 BIB bullets last week, and asked his recommendations on twist and velocities. Among other things, he said bullet blowups (by any manufacturer) can be a tight-barrel problem. As I remember, he and a friend had two identical guns with the same barrels, same chambering, but one barrel was slightly tighter. I think it was a couple ten-thousandths. The first gun shot a particular bullet/load with no problems, but the same bullet/load in the tighter barrel experienced bullet blowups. Since Jeff has a new Bartlein, this may be the case if he is shooting the same speed and twist as his last barrel.