Should I build 12" or 16" AR?

[drewthebrave]

12" is plenty for what you're trying to do IF you can hunt with lead ammo. My state requires lead-free projectiles -- which have a bit less expansion range at Grendel velocities than lead ammo -- so I like a longer barrel at 18" for some more range.

For example, Hornady 123gr SST expands out to ~400 yards (down to 1800FPS) from my 18", but the 100gr Barnes TSX is only good for ~280 yards (2000 FPS expansion threshold).