I have a Polytech. Headspace was excessive. It would close on a field reject gauge. I bought a brand new TRW M-14 parts kit from Orion 7 and stirpped the forged receiver and built a brand new rifle out of it. Milspec forged receiver, USGI TRW parts. All for just under $1000.
Read the Fulton armory FAQ on them. It is very accurate. Many Chinese M-14s will headspace fine, and as long as that's the case, they work well. It's just with the soft parts, the headspace can go outa whack quick. I chose to rebuild once the gun became unsafe to shoot. I am dubious of the various "re-heat treatments" that are available. Fulton will do a great job, but their price is now something like $950 to put on GI parts, and even then some of the Chinese parts may be OK to use. I wanted the strongest, closest to milspec rifle I could get, so I built it myself. It was one of the easiest builds I've done on anything. The receiver is top quality.
Ross