Hi folks. New to forum and reloading. Just bought a del-ton echo 316H and looking to get into reloading. I have a Lee breech lock challenger single stage press. Had allot of trouble finding powder so took what I could find. I ended up with IMR 4320. Anybody building ammo for AR with this powder? Also wondering about use of the varmint nightmare bullets in a 16" 1:9 barrel. It's a faster twist than spec'd but with a shorter barrel I was thinking muzzle velocity and hence rotational forces would be lighter with shorter barrel. Thanks!