I am attempting retro-rebuild of an XM16E1. I have upper minus BCG and charging handle. Also have buttstock , Edgewater buffer and spring.No lower...believe S/N might be 711XXX. Barrel has no proof markings and was heavily rusted and from what I can tell not chromed. Where can I get a 20" parkerized .625 barrel with 1/2 x 28 thread that is chromed? I want to use it when I am finished. Also parkerized FSB,triangular handuard cap and  dust cover? I would like XM to be accurate but want the chromed(modern) barrel. Any advice and/or suggestions on this rebuild would be greatly appreciated.

If it's an original XM upper, I'd use it. That barrel may not be as bad as you think - although most of them got shot out. Regardless, we could help you more with some pictures.

How many posts are you going to make with the same question?

Replied to the other two. Let this one die.

http://www.ar15.com/forums/t_3_123/657061_XM16E1_retro_rebuild.html

http://www.ar15.com/forums/t_3_123/263900_.html&page=11&anc=6614416#i6614416