Sorry guys, I'm sure this has been discussed several times before, but I couldn't find the thread(s). I have a new baby on the way (Colt 6921 SBR). This is my first NFA item and my 2nd AR. Do you think this package is worth it? Colt already makes a great quality product but... I don't know. Anyone here have this done to their gun? What all do they do (details)? All they said on their website was barrel mods, bolt mods, gas system mods, and a new buffer assy. Also, apparently the 6921 comes with a S/A bolt carrier. Should I buy a F/A carrier? I've heard it is more reliable, is this true? Any other benefits? Any other recommendations? Thanks!