i currently own a bushmaster pre-ban w/a 16 inch barrel, extended car suppressor included, perm. mounted, of course.  <500 rounds fired.  i am getting a m4a3 14.5" w/phantom suppressor perm. affixed.  should i get the bolt and bolt carrier, or just the upper/barrel alone and use what i have?

With this few rounds your existing bolt and carrier will work fine.  Swapping the bolt back and forth will accellerate wear on the locking lugs though.

You keeping the 16" upper?  I'd at least get a new bolt with the new barrel (the receiver isn't part of the equation) and keep the bolts with their barrels all the time.  You'll tire of this if you switch uppers a lot, so get a carrier too.

If you shoot a lot get the M16 "gage, headspace, field" and check both uppers/bolts annually.  Comercial gages are undersized and will make your barrel gage "worn out" when it's still well within specs.

The M4 upper and barrel are Bushmaster?

-- Chuck

The M4 upper and barrel are Bushmaster?

-- Chuck

yeah, sticking w/bushy.  i really like the quality.  guess I'll get the bolt w/the upper.  Just hoping someone could justify the cheaper route so i could order it sooner.  :)

I'd spend the extra 4100 (?) and get the bolt.  You want the bolt to wear and match the upper receiver as best as it can.  Besides, having a spare bolt is always a good thing.