OldCannon wrote:If you're just a plinker, 1:9 is perfectly fine. If you need to drop steel (or, um, other heavy targets) at 400-500m, you're gonna want to shoot 77gr heavies with a 1:7 twist.
Honestly, 1:9 is perfectly fine for 90% of the AR owners.
I had no issues dropping "heavy targets" at ranges up 600-700 by launching a 62gr out of my m16a4 which had a 1:7. If you just plan on shooting nothing but cheap 55gr stuff 1:9 is fine, any thing else get a 1:7 you can do anything with it.
Also if your not going to be kicking in doors get a 20in upper 16s are cute and all tacticool, but they are loud and the loss in accuracy is not worth it. I have never had anyone out gun me with their 16 when I'm running my 20. That being said the collapsible stock is the best thing since sliced bread.