Just looked at the M4 Dissipator on the Bushy web site.
That is one of the dumbest things I've ever seen! The M4 contour doesn't do a damn thing for you in a 16" Dissipator. The M4 cut for the grenade/flare launcher mount is under the handguard, ergo, making it useless.
Just make it a lightweight barrel all the way, skip the stupid M4 profile, and save us all some money and physical weight.