I have a Colt M4 and I'm interested in a new pistol grip and new handguards. I have a friend that has an Ergo grip and I like it. He also went to a free-float with a new gas block, but I want to keep my factory sights. I'd like the free float, but don't really want to disassemble the barrel to install it. I know there are a few companies that sell FF handguards that will install without disassembly, but I'm worried about durability. I don't really need 4 picatinny rails like most of the hanguards have, but I would like a short rail on the side for my surefire. Want to know what ya'll suggest.