What kind of accuracy can I expect out of my 20 inch, 1:7 inch twist barrel at 100 yards, with 5.56 M193 55 Gr. and factory .223 55 Gr.?
Would the groups be just as good as they would in a barrel with a 1:9 twist?
Should be just as good or better. I built a 20 inch A2 with an FNMI USGI barrel that shot 2" groups with irons a 100. This was with Hand loaded Hornady 55 gr FMJs.
XM193 probably won’t shoot as well. But a good 1/7 should be a 2-3 MOA gun, no problem.
I have a friend who has a scoped 20 inch Colt H-Bar. He shot some Factory loaded Federal 50 grain Hollowpoints at a three hundred yard target and got a 4.5 inch 10 shot group. He was sure the accuracy would be poor with the faster twist and was shocked at the tight grouping he produced.
The errornet Kool-Ade drinkers would have you believe a 1/7 twist is no good for bullets lighter than 62 grains. The whole thing is they are simply repeating garbage while never attempting to test they hypothesis for themselves. It ain’t hard and it ain’t rocket science.
It will be fine.
Likewise, 6.8 people often think that the bullets which are wonderfully accurate in 1/11 twist are suddenly bad in 1/10 twist. I doubt you could measure the difference.
Thanks for the replies, I have the Palmetto State Armory 20 inch barrel, made by FN.
I think the weak link there is the ammo, not the barrel or the twist.
55gr FMJ rounds aren’t that accurate, and at 5.56 velocities, even less so. Molon posted some testing, and the one exception seemed to be the 55gr FMJ Hornady bullets in a hand load. But, its hard to compare hand loads and factory loaded ammunition.
If you want a 55gr for shooting paper, the 50/55gr VMAX is amazing.
Thanks for all the information, I typically prefer the 62 Gr., but 55 Gr. is more plentiful. By the way, anyone have any recommendations on any good priced 62 Gr. ammo?
Need lead core ammo for the range rules.
Yeah… about that… 55gr and 62gr, all the surplus stuff isn’t accurate by a precision shooter’s standards. If you want to see what your gun is really capable of then buy a couple boxes of different match grade factory ammo’s, try them each, and you’ll have a better idea.
If you don’t want to spend the money and you’re fine knowing what you know now, then a good place to buy some bulk 5.56mm is Wideners, last I heard this was the best online deal for 55gr.
http://www.wideners.com/itemdetail.cfm?item_id=9017&dir=18|830|845
I’m sure they have some 62gr stuff too.
Accurate enough for what? Two weeks ago I was hitting steel at 300-500 yards with my SBR using XM193. I guess it all depends if you are playing sniper or just trying to get some trigger time.
If I were shooting for groups, on paper like my post suggested, 55gr FMJ wouldn’t be my first choice.
If you’re banging steel, sub moa capable ammo isn’t required, as all you’re going for is a hit anywhere on the plate.
The cannelured 55 Hornady FMJ can be found factory loaded, new or reman, from Black Hills.
If you want a 55gr for shooting paper, the 50/55gr VMAX is amazing.
Agreed. See also the Sierra Blitz King in 55. Both are superb varmint rounds.
Good to know about the Black Hills 55gr. I always wanted to know what bullet they were using.
I have read good things about the Blitzkings too. One of the more accurate rounds I’ve seen tested.
I’ve used BCM’s 20" M16 barrel with XM193 to handloads using 75 gr Hornady BTHP and with irons I can group just under two inches at 100 m. Although with the XM193 and other [terrible] military ammunition it’s a good day if it’s under 4". For all intents and purposes it gets the job done within the ranges it’s made for. I’ve ran 55 gr V-MAX handloads through it with excellent results so far. I’ll put a scope on it soon and try shooting for groups in the coming weeks and report back. The FN and BCM M16 barrels should be nearly identical in performance.