i have seen colt 1-7 twist carbine with Barnaul ammo 55 grain -the velocity is lower and keyhole at 25 yds... but a 20'' barrel 1-8 works nicely and no key holing ..... the bullet is smaller length than 193 too
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i have seen colt 1-7 twist carbine with Barnaul ammo 55 grain -the velocity is lower and keyhole at 25 yds... but a 20'' barrel 1-8 works nicely and no key holing ..... the bullet is smaller length than 193 too
thanks for the replies. I wasn't going to name names as I wanted to protect the innocent. now that I am certain that the upper is not at fault I'll try to fill in te blanks...
the upper is a BCM middy with less than 500 rds, no carbon buildup that I can determine and no interference from the A2 FH. it has always shot all other ammo very well so I'm sure at this point it's not the upper.
on the other hand, the ammo is Atlanta Arms, which also has a very good reputation but I was not just getting misshapen holes in the paper at 25 yds. - it looked like the bullet struck the paper perfectly sideways! I've never seen that before.
the reason I came her to ask is that I suppose the ammo is loaded to lower velocity but that seems counter intuitive to me.
a bigger slower bullet needs a faster twist to stabilize, that I know. I also know that a 55gr. should have no problems with 1/7" twist so long as the velocity isn't so great as to cause destruction of the bullet due to too high rpm.
but putting a short bullet, which normally do well with a slower spin like 1/9", through a 1/7" twist would seem to perform better, not worse, when slowed down, right???
I'm puzzled...
never push a wrench...
Do you have or have access to a bullet puller? Check the bullet it self for roundness..
Are all shots hitting the target? What kind of groups are you getting? Generally, bullets hitting sideways at 25 yards don't hit the target very often. Some bullets don't poke holes in target paper, they cause tears.
1 in 7 is a pretty tight twist. Bullets with soft jackets will skid instead of being properly spun by the rifling
no. er I mean yes, I do have a bullet puller but I don't have any more ammo.
I took some friends who were in town over to put a few rounds through the gun and I ended up forgetting my rifle ammo. they bought a box of 50 from the shop while we were there and this is what we experienced with the first 20 or so.
I had another rifle with 1/9" twist and the ammo shot fine in it but I'm not willing to buy any more of that ammo.
and btw, I just put 500 rounds of Privi through the gun this past weekend and all was as it should be so I'm not stressing...
never push a wrench...
What is keyholing?
I must study politics and war, that our sons may have liberty to study mathematics and philosophy. - John Adams
The AK guys are all about the reach around. - Garand Thumb.
the ammo was Atlanta Arms which has, I thought, a pretty good reputation.
the same rifle shot 500 rds of different 55gr. ammo at a one day training course here this past weekend and was as good as should be expected so I've eliminated the rifle as the source of the problem.
and the Atlanta Arms ammo also shot just fine in a 1/9" twist Armalite I had along that day. it's just that the BCM middy 1/7" and that particular ammo was a bad combination.
never push a wrench...
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