I see that PSA has their barrels listed at 1 in 10 and the CMMG's are 1 in 14 or 15 in

What is the best rate for a 9MM AR

Thanks,

Red

Std from WW2 for subguns been 1x10..  pistols through yrs been 1x16, couple 1x10..

All my 9mm barrels (AR-15, M11-9, and Uzi is 1x10)

I just checked the CMMG site and their 9mm barrels are listed as 1 in 10".  Perhaps they had a hiccup on their new site when you checked.

I doubt that there is a best rate.  If there is, it would be only for one length of bullet.  Other bullet lengths, (and you can usually use weight instead of length, but it is the length which is most important).

1 in 10" is way faster than necessary for 9mm accuracy.  Look how accurate .38 Specials and .357 magnums can be with longer bullets than typically used in a 9mm.

In WWII, the 1 in 10" twist became popular either because the tooling was readily available, or they wanted a quickly rotating bullet because they believed it would penetrate better.  Maybe even both.

Now that we have viable hollow point bullets, the theory may be to make the bullets expand more quickly.

For accuracy, you don't need that much twist in a 9mm.  But, since we so rarely shoot 9mm at long ranges, and people have low expectations of long range pistol caliber accuracy, most will get by just fine with a 1 in 10" twist.

My GLOCKs are 1:10 and my Kimber is 1:16.   The Rock Rive Arms 9mm AR I had was 1:10 also.