nothing to do with accuracy...... i strongly disagree
here's the scoop
manufacture is of no issue, get one that fits your rifle. I don't buy into the hype that a trw is worth any more than one of the other usgi bolts.
In most cases, 99% of the used bolts i've handled have been suitable for a install to a norc/poly set up.
what i have found is that in general, a usgi bolt meets the correct receiver tolerances much better than a chinese bolt, which equates to less slop in the movement of the bolt through it's entire cycle and particularly as it cams through the receiver bridge.
what a usgi bolt allows you to do is convert your m14 to match .308 specs. "Match" specs are called that for a reason, a match rifle is an accurate rifle..... a tight chamber leads to increasing accuracy if all other variables are brought to that level.
this means that if you install a usgi bolt to your barrelled action and it is correctly lapped in to mate the bolt lugs, the headspace will shrink from 7.62 nato to a very tight .308
generally about 1.631 to 1.632 is acceptable for a battle rifle type .308 match chamber.
if installing a usgi bolt and you get nato headspace of greater than 1.636 , I would not even use the bolt and stick with a chinese one. likewise we never.... ever lap a usgi bolt out to nato spec chamber.... this can get you too deep into the bolt lug hardness.
every usgi bolt swap i have done has increased accuracy using .308 ammo
as stated above, they are pricey, illegal to import unless you import an entire rifle (ie LRB). some are to be had for big $$$ here in the ee.
I should add that by and large the newer imports have considerably "better" headspace than previous years and are averaging 1.636 to 1.638 headspace measurements.... which only puts you a couple thou over Nato Match of 1.6345 so the days of getting strung out on having a usgi bolt are pretty much moot. even safer than before to shoot both 7.62 nato surplus AND .308 commercial thru the same pipe.
