New to this site, looking for advise and input from professional colegues.
I'm a second generation gunsmith and graduate from Trinidad State. Have seen over the past few years of Win M70's in the WSM calibers with factory defects stemming from the production year of when Winchester stopped production. It appears that many of the last units were shoved out the door as "Parts Guns". I have one in particular that is a thorn in my side.
So far I have had three come through my shop. The first would not shoot anything less than a 3" moa reguardless of ammo, due to excessive tooling marks full length of the bore.
The second had the mount screw holes so far off it was near impossible to mount anything up close to center.
But the one that is still with me is a 300WSM that locks up after firing. Checking the chamber with my bore scope, I could clearly see that the chamber was clearly rough with reamer chatter marks. after checking the headspace, which is tight, I polished out the chamber and neck. I then rechecked the headspace which is now well within specs, but she stills locks up. Checking the fired brass reveal nothing and is within specs.
I've never actually taken an M70 apart, but I just pored over some diagrams. Not to state the obvious (I'm just a novice so I don't know what's obvious to a trained professional or if I'm just being stupid) but it has to be the recoil knocking part of the bolt around. If the headspace wasn't the issue, consider what components may be coming out of place and sticking where they shouldn't be.