Got an M5 also FDE upper blk lower but with a keymod handguard.I also got the Nickel boron BCG.Had a very hiccups with FFE and FTF,changed the recoil system to Armalite parts and resolved the problem.I take it since thier were no mention of issues you had none.I had the barrel cut down and added a Battle Comp for a 16.1 overall lenght.Lastly put in the LaRue MBT trigger with LaRue A-Peg rough texture FDE grip.