In the market for a 5.56 Carbine

[iraiam]

I'm not new to the AR Platform, I own two rifles; an older colt SP1, and a Colt match grade A2.

But now I want a Carbine, I think I have settled on the Colt M4 Carbine, I kind of like the Colt. I was a little surprised to see it had a 1/7" twist though.

My NM rifle has a 1/7 also, it shoots 75-77 grain bullets extremely well, 55 grain not so much.

What is the standard for Carbine ammo? (if any)

[FloridaVeteran]

iriam - I don't know the answer and don't mean any offense, but I think you'd get better results by posting your question with a different title, like "What is the best twist for a 5.56 carbine?

Unfortunately, I'm not experienced enough on the forum to tell you how to get that done.

[TheSILENTtype]

what standard are you referring to? I am not sure I understand the question.

Are you asking what is the most commonly used grain in a 5.56c community , or the common twist amidst these carbines in general?

[Quentin2]

If you plan to shoot 75 gr in the carbine then Colt's 1:7 is what you want. Really doesn't matter whether the barrel is 16 or 20".

[5.56RifleGuy]

You might try asking KraigWY in a PM. He shoots these types of rifles competitively, reloads, and all that kind of stuff I believe.

[TheSILENTtype]

I enjoy a 20" chr.lined 1/7". Some will surely disagree but nothing else has such a wide range of ammo choices in my local.

At any rate :

20" for service rifle or longer distance use - 300+
16" and below for CQ or LW carbine manuverability.

1/7" and 1/8" for beyond 70gr. 1/9" is optimal for 55 / 62.

It just took a few re-reards to get the question.

[sailskidrive]

The US Military uses 62gr, if that is your question....

[TheSILENTtype]

Add - The USMil uses 1/7" for a very wide range of ammunition function.

tracer,ld etc.