I have an older (1980's) vintage COlt SP1 AR-15, and am also waiting on delivery of a new RRA AR. My older Colt has the 20" barrel with (I believe) a 1:12 twist. The new RRA will have a 16" barrel with a 1:9 twist.
I am about to start re-loading again after a long hiatus, and started re-evaluating bullet weights. All of my current .223 ammo inventory is 55 grain FMJ, mostly my old re-loads with just under 2,900 FPS muzzle velocity. I have read a few cautions about light weight (55 grain) bullets not working well in rifles with "fast" twist rates of 1:6.
What is the collective experience out there with using 55 grain FMJ bullets in AR's with a 1:9 twist. Do these bullets perform well, or do I need to start loading the heavier 62 grain bullets?
Thanks in advance,