Hi,
I'm putting together an XM177 clone and am wondering if I should use the bolt that came with one of the M16A1 uppers they're selling these days.  It's marked MPC and looks to be in good shape, but I've read that a bolt wears to match its barrel extension.  With a new barrel, I'm guessing I should probably run a brand new bolt with it.  I like the old bolt just for the "correctness" of it for a clone, but it wouldn't be a big deal to run a new one, either.

Thanks

It's your call, but headspace it first.  If it fits, use it.  If not, keep it as a momento and pick up a new bolt.

I would get some 5.56 headspace guages from brownells.  If you are going to be dealing with AR alot, they are a great investment and readily available.

i plan on using a new bolt with my build but using the original carrier.

its a clone, not the real thing so i rather use a new bolt. also agree that if you do plan on using used parts checking headspace isnt a bad thing and should be done.

A few years back I bought a bunch of milsurp Viet Nam era M16 bolts, because the price was only $15 apiece, complete w/extractors & ejectors.

Headspace tested all of them in 4 different ARs, all w/200 rounds or less (2 were brand new barrels).  Only one of them would close on the MAX guage, and it showed OK with the FIELD guage.
And the one that I had to go to the field guage on was so old that it still had the white extracor insert.  The others were all blue insert.

Put Wolff extraor springs in, and still have, and am regularly using two of them in my ARs.  Do what you feel best with, but my experience is that those Colt M16 bolts are tough puppies

Thanks for all the help guys.  I just pulled it apart and it has the blue extractor insert.  I already have headspace gages, I'm just waiting on the barrel so I can check it out.