What is the difference between the R-4 profile barrell and the heavy barrell profile.

The R4 barrel is M4 profile, but only beyond the handguards.

A real M4 barrel has a government profile under the handguards, and a  barrel cut slightly past the front sight base to accomodate the mounting of an M203 grenade launcher.

The R4 barrel has the cut on the exposed part of the barrel, but is a standard heavy barrel under the handguards. Basically, no M203.

A heavy barrel is a standard barrel that has a very flat profile and a wider diameter than government or M4 profiles.

M4 barrel.


R4 barrel.


Heavy barrel. (HBar)

Thanks man that was a really good explaination.