Our Mk4 handguards along with any freefloating AR15 type handguard should work on our Mk4, Mk9, MkG, MkGs, Mk17, Mk10, and Mk57 lines as the upper receivers are based off a standard Mil-Spec upper receiver.
Our Mk3 handguard along with any freefloating handguards compatible with DPMS Gen 1 LR-308 High Pattern uppers/rifles should work on our Mk3 and Mk47 platforms.