the 7.62 firearms bolt and any usgi spec bolt WILL require correct fitting/lapping upon install. These will not be drop in parts. They may close on an empty chamber with full lug engagement BUT fitting and lug lapping are essential for correct and safe head space.
It's not rocket science and can be done at home by the layman BUT you will need a correct headspace guage for the chamber dimensions you desire. It has also been my experience that the only option for chamber size will be .308 commercial or in the neighborhood of 1.630/ 1.631. Which is good..... excellent in fact, but will mean your rifle's chamber will not safely chamber 7.62 nato as it will be a 4 or 5 thou crush fit and can lead to out of battery or slam fires. Lapping the new bolt out to match 7.62 nato headspace (1.6345) or even close to that risks cutting through hardness layers on the receiver and bolt and IS a #### loss inducing siuation in any rifle

Not trying to spread doom and gloom or panic about installing a usgi bolt or a 7.62 firearms bolt, but folks should know that they should not expect a drop in and shoot item.
for those wanting these parts fitted, thier are plenty of us here on cgn that can walk you through lapping in a bolt. It's a rather interesting and gratifying job when you can do it yourself and see the results down range when yer done
as for bolt assembly/disassembly , we do have the M14Doctor bolt tool availlable in good supply, works awesome, I use mine daily

visit m14doctor.com for details,
info@m14doctor.com to order.