SapperLeader,
The Carbon 15 M4 rifle seems to be an AR15 with a carbon lower and upper receiver as opposed to the regular Carbon 15, which is more of a lightweight rifle with an AR15 operating system. Every aspect of the Carbon 15 was designed to be light (carbon fiber stock, recoil tube and a low profile fluted barrel) and negated the use of standard AR15 parts.
Natedog,
I believe that the rifle uses a true M4 profile barrel and not a heavy barrel. If you compare the weights of the C15M4 and the M4ogary that Bushmaster makes, the weight difference is .64 lbs different. This is ball park for the “3/4 of a pound lighter†claim they make. Also Bushmaster doesn’t make a barrel with an M4 profile in front of the gas block and heavy barrel under the hand guards. If they put their Superlight barrel on the rifle though they would really be cooking with gas.
Victor