Best round for a Colt SP 6940

[huzyerdaddy]

Hi Guys;
I have a Colt SP6940 with a 1:7 RH twist 16" barrel and was wondering about the best bullet weight would be, and the reasoning for it. Thanks in advance for your insight...

 

[mvician]

62gr and up to 77gr, although the 55's will work fine.

Try some of each and see what your rifle likes best.

 

[sloughfoot]

The best bullet weight for what? Accuracy, hunting, etc?.....

 

[figley]

The best bullet weight for what? Accuracy, hunting, etc?.....

maybe he just wants one that will make a loud noise? shoot fire?

OP, maybe you could google around, and see if somewhere, some wise souls might have compiled a whole ORACLE of information about AMMO for rifles, like your Colt, or even other AR-15 rifles?

Myself, I have been on a quest lately to find ammo that will provide reliable fragmentation, or other terminal performance, at typical HD/SD ranges, from a 10.5" 1:7 barrel. I finally settled on Mk318 mod 0, and/or, a Hornady TAP 75gr T2 (equivalent, for us less equal animals) load, made by BVAC.

The 62gr OTM/RP bullet actually has two deep grooves, that aid in its terminal performance. The 75gr cannelured bullet, even though its muzzle velocity is somewhat low, evidently has a lower fragmentation threshold than XM193, due to its greater surface area, and can be relied upon to fragment out to 46m, when shot from a 10.5" barrel.

Length affects velocity, but not accuracy. IIRC, out of a 16" barrel, XM193 retains fragmentation velocities out to almost 150m. It follows that frag. range of any ammo would be extended, when shot from a longer barrel. For this reason, I have been giving serious consideration to changing my plan, from a 10.5, to a 12.5, or even 14.5" barrel.

The current trend in barrels, is 1:7, CHF, double-CL, MP/HP tested. Everybody's doing it, but then again, a little mouse told me that all the manufacturers are putting out piston systems, with full knowledge and understanding that the whole concept may be flawed.

1:7 is expected to stabilize anything 55gr or greater, but as always, buy a few boxes of each round you may want to shoot, and do your own proving.

 

[huzyerdaddy]

Thank you Figley for your insight, much appreciated...