Re: 1:8 or 1:9...
I am of the opinion that 1:8 is the perfect twist rate for a 223/556 AR15. That twist rate will work with EVERYTHING that will feed from an AR magazine.
My RRA Predator Pursuit rifle has a 1:8 twist. It will easily shoot inside the company's 3/4 moa accuracy guarantee with every bullet I have shot from the 40 grain varmint bullets to the 77 grain match bullets. In fact it works so well, I'm looking to re-barrel my bolt action 223 with an 8 twist barrel.
.308 Howa 1500, varmint supreme. 24" .820 barrel, Roedale precision brake.
.223 Howa 1500, varmint supreme, 24" .820 barrel.
RRA 20" predator pursuite, Magpul PRS, ALG trigger,