Light Bullets in 8 twist 6BR

[jesilva]

I have an 8 twist 6BRthat currently shoots 70 gr Sierra Matchkings very well. Will any of the lighter Bergers work without blowing up. the reason I ask is because I tried the Barnes 68 gr Match Burner and they vaporized, even at the lowest velocities.

 

[cocopuff]

I find that hard to believe...I have shot them as well as berger and bart's..both 68 gr..and hornady 65 gr.....With H4895...And if I do my part,they
shoot good..only to 300 is all I have tried though..

 

[jonbearman]

How do you define low velocity?

 

[jesilva]

What I meant was velocities generated at the low end of the recommended charge weights. In my first attempt at testing, I used IMR 8208 XBR with charge weights from 29.8 to 32.5. This generated velocities from 3223 at the low end to 3518 at the top charge. Bullets started to vaporize at about 3370 fps. I then tried some with charge weights slightly lower that the 29.8 (I can't find the data), but they still vaporized apparently at a velocity below 3200. Just curious because I shoot 70 MK routinely at a velocity of @3272 without incident.

I was really wondering if any of the 65 - 68 class target bullets would have the same problem.

Jim

 

[oldhoward]

I have shot 55 Nosler bt's and 58 grain vmax out of my 8 twist at 3700 to 3750 fps. Never had one blow up. 68 grain bergers worked ok for me too. Try the 55 grain bt's I think you will be happy and surprised at the accuracy.
Powder was rl7 case lapua, ccibr4's, be careful in very hot weather with load development, back off the powder.
oldhoward

 

[searcher]

I too shoot the 58 V-Max'es out of my 1-8 w/great accuracy for varmints and NO problems coming apart. Haven't tried the light-weight Bergers or Barnes though.

 

[Tokimini]

My 6BR with an 8 twist McGowen barrel likes the 68 gr Bart's the best. Here's a group I shot this morning, five shots at 100 yards.

 

[cocopuff]

My 6BR with an 8 twist McGowen barrel like the 68 gr Bart's the best. Here's a group I shot this morning, five shots at 100 yards.

thats great shootin dude......

 

[Tokimini]

My 6BR with an 8 twist McGowen barrel like the 68 gr Bart's the best. Here's a group I shot this morning, five shots at 100 yards.

thats great shootin dude......

Thanks

 

[CooperNV]

I'm shooting 62gr Barnes VG's in the 3500fps range in a 8 twist lilja. Good accuracy on ground squirrels and chucks. I like the length of the VG's as the barrel was throated for 107 MK's.

 

[jesilva]

It is possible that the throat is a bit rough, the barrel has about 3500 rounds thru it, but it shoots the 70 MK at about .25 MOA consistently.

 

[fm1947]

Nice shooting, how did you find center to center, when I do that, occasionally I just say, well that's a good one.

 

[Tokimini]

Nice shooting, how did you find center to center, when I do that, occasionally I just say, well that's a good one.

Measure the widest part of the hole with a dial caliper then subtract the bullet diameter. That will give you the center to center group size.

 

[fm1947]

aw ha, I never bother to do that unless I measure a single bullet hole because it doesn't work exactly , example a .243 bullet will hardly ever make a .243 hole, when you have a group like yours if a dime covers I'm good with that, I have never shot group competition, I wonder if that is how they do it.

 

[Ghansen]

I'm interested in shooting some lightweights myself, am curious as to what freebore you have. I know mine likes 107'smk and I'm not sure of my FB, but I would be more than happy if I could shoot 68+ at shorter distances. Love the group above too!

On group size.....I leave it to the experts
(Extracted from article 6BR Texas Tack-Driver)
* Editor's Note: You can see from the target photo that USMA89 figured group sizes by subtracting .243" nominal bullet diameter from edge to edge measurement. We've found that 6mm bullet holes in paper are usually around .220" in diameter. On this site we also normally try to measure groups center to center when possible. This avoids uncertainties involving the gray area surrounding the hole. Measuring that "wallet group" more conservatively with a .220" bullet hole would increase the group size by 0.023" to 0.135"--still pretty amazing for 200 yards.

 

[cocopuff]

I shoot 68 and 70's with great success at 250 yards using H 4895 and cci 400 primers..Varget Does not do it for me at all...And you do not have to have
them screaming..