I just got finished putting together my RRA lower and parts kit with the fixed 6-pos stock. Looks great! Anyhow, now I have to start looking at uppers. I know I want an RRA upper, however I'm a bit confused on some things. I want a 16 inch barrel, and I want it to be crome-lined, that I know. On an M4 upper, Does the end always have either a muzzle brake or flash hider? Or can you build an M4 upper that has neither at the end?If I bought an RRA M4 upper in post ban, since my lower is post ban, does that mean it comes with a muzzle brake? The muzzle brake is louder right? On a CAR upper, lets say the 16 inch one with the short CAR handguard, could you just switch out the CAR handguard with an M4 handguard no problem? What is the difference between the M4 upper and the 16 inch upper with the CAR short handguaurd? Is it just the feed ramps on the M4 upper that makes the difference? I really like the way the M4 looks, however I don't know if the muzzle brake makes it louder or not, and I don't want an obnoxiously loud gun. Any help? Sorry so many questions.