Heavy Buffer H1
AR15 carbine buffer weight is a fundamental part of the cycling operation of any ar15 carbine.
In general terms, the shorter the barrel the heaver the buffer that is used.
But with many people doing custom builds, as well as barrel gas ports having a wide range it is common for guns to be over gassed or under gassed.
Another issue is if you are shooting standard load 223 Remington or full NATO load .556×45 ammo.