I can technically do it for PCGuns, I headspaced his FAL for him last Fall. PCGuns is also my FFL sugardaddy, I highly recommend him for FFL transfers, that being said....I suggested having the rifle sent to John Tanks at Tanks Rifle Shop in Nebraska. Headspacing an M14 rifle is a tricky process and not saying the Gun Doctor can't do it, I'm sure he could but I wouldn't bring my M14 there. I used to live at Rodenburg and Lake years ago, we used to drive down Lake Street late at night and yell "Hey Dad....what are you doing." at the old dudes going into Zebulon, the porno shop on lake Street.
Anyway, the M14 has a short chromelined chamber, making the chamber un-reamable for headspacing. To headspace the rifle, the lugs of the bolt must be lapped to get the bolt to slide in to battery and to acheive the correct chamber dimension, in this case, you'd be looking for 1.63215 for NATO 7.62 x 51 headspace.
DSA headspaces their rifles at 1.630" which is GO for Winchester .308 specs, I prefer the NATO headspace on a .30 rifle although the Winchester specs supposedly makes for a more accurate rifle, I think this point is only relevant with bolt guns. My M1A is extremely accurate and it's a standard with all GI parts.
The standard M1A is a solidly accurate rifle as demonstrated by Tim84K10 and myself, shooting our M1A's in tandem at a Tide bottle in the pit during Icefest '06 at the pit last weekend, both M1A standards with NATO headspace specs creaming the hell out of that soap jug, I wonder if that is what the VC felt like when our boys were frosting them with M14 fire? LOL
M14 companines like Smith and Fulton are also TOP NOTCH but the hands on service is not there like at Tanks, John will talk to you for an hour on the phone about just your op rod, he is a good guy and an M14 guru.
tanksrifleshop.com