I have a J series, that I bought new, so no one else has worked on it. Some time back I converted it from 243 (factory) to 308. I have since decided to go back to it's original barrel, which is a 20" 243, that was cut and drilled for sights.

Now the issue comes when I set the headspace with my Forester gauges. If I align the sights to be centered as they were from the factory, then I can close the bolt on the no-go gauge. It takes force to close, but not much.

Now keep in mind I put a few hundred rounds through the factory setup, both factory ammo and handloads, with no apparent headspace issues.

Is it a difference in how they set headspace (1974) or is my gauge off, or was it off from the factory, or is it fine the way they had it set? I want to leave the factory barrel on it for nostalgia but not with the dovetail setting crooked, and not if it's unsafe properly aligned.

Could headspace specs have changed since then?