I'm planning on sarting my first build in the next couple of weeks. Actually planning on picking up a Bushmaster Carbon-15 reciver at the next Houston gun show in 2 weekends. Anyway, I'm planning on going with a 16" fluted heavy stainless barrel. I would like to load 77 grain HPBT for my primary round but I would also like to be able to shoot the 55 grain plinking ammos too. Can I get away with a 1:7.7 twist barrel or is that too fast for 55 grain? Since it's hot and humid in Houston almost always I think stabilizing the 77 grain should be reasonable with that rate. I think I could even go a little lighter, mabey 1:9 but I'm not sure what it would do to my groups at 300 yards. Any suggestions?

Id have to say any where from 1:7 to 1:8 ratio would do good... 1:8 is an excellent twist ratio for the 80 grain .224 bullets and it will handle the 55's pretty well too...