Which seems more accurate in .223, 62gr. or 55gr. FMJBT?

[Kosh75287]

I know that this has VERY MUCH to do with barrel twist rate, so I haven't forgotten about its effect.
I have nonetheless read//heard from people, who have shot more .223/5.56x45 than I am ever likely to in the rest of my lifetime, that the 55 gr. BTFMJ (M193?) projectile tends to be more accurate than the 62gr. BTFMJ (M855?) at (for me) more relevant/likely combat ranges (say, 0 to 400 yards). The information I got was that, even for barrels with twist rates optimized for the 62 gr. BTFMJ, the 55gr. projectiles tended to shoot tighter groups.

From people who would know better than I, the putative cause was that the .11" steel ("penetrator"?) core in the 62gr. projectiles was positioned with just very slightly less concentricity than the conventionally-cored 55gr. projectiles. Any opinions/input/surmises/cognitive spit-balls would be welcome.

 

[Steve_In_29]

This is VERY rifle and even ammo brand specific and you will have to see what your particular rifle happens to like best.

It has been shown time and time again that just because certain ammo shoots well in one person's rifle that there is no guarantee of it doing so in another's. Even when the rifles are the same make/model.

 

[james.long48]

No two barrels are the same.

Sent from my SM-G930V using Tapatalk

 

[easy rider]

I shoot primarily 5.56, although there isn't a big difference, mine seems to shoot a bit better with 62 gr. at 100 yds. I also don't shoot the cheapest ammo often.

 

[V-Tach]

This is VERY rifle and even ammo brand specific and you will have to see what your particular rifle happens to like best.

It has been shown time and time again that just because certain ammo shoots well in one person's rifle that there is no guarantee of it doing so in another's. Even when the rifles are the same make/model.

No two barrels are the same.

Agree......

 

[deemus]

I shoot 55s in both a 1/9 16" carbine AR, and a 1/9 24" varmint bull barrel AR. I tuned my ammo to the carbine, but the varmint barrel is even more accurate with the same ammo.

It will matter if you are shooting factory loads or loading your own. Barrel length and twist also affects it.

 

[ROGER4314]

1:9 twist and 55 grain projectiles are the perfect storm in AR 15. I won prize money at 600 yards with that combination.

69 grain SMK bullets and 1:8 twist barrels are similarly a perfect combination. I shot the best scores of my life in competition with that match.

Flash