Now you've made me nervous!
When the rifle was built last year, it was head spaced, but I don't think it was head spaced correctly. The guy who did it used a fired 308 case, which he said was "properly headspaced"?, rather than a go or no go gauge. Knowing next to nothing about FAL's, or head spacing at the time, I thought nothing of it. Now, I think that it was way off.
After the rifle was built, I took it to the range twice, and I had 2 problems:
1) Failure to feed. Every other round would jam. Even with the feed ramp polished, I could not get it to reliably feed when cycling by hand or firing.
2) Even if it would have fed, the rifle would not function firing semi auto, even with the gas port all of the way open. It was a bolt action FAL. I thought that the gas plug was bad, so I bought a new one of those when I bought the bolt and carrier.
After a total of 40 rounds fired, I gave up on it and put it in the back of the vault.
This fall I decided that I wanted to get the FAL going, so I dragged it out and headed off to get it head spaced and looked at.
The first thing the smith noticed was the bolt. It was in bad shape, and he suggested getting a new bolt. I ended up buying a new carrier too (from Dans Ammo), and they looked great. Putting in the new bolt and carrier into the rifle, I tried manually cycling the rifle, and it did feed reliabaly out of 3 of the 4 (probably bad) magazines that I have, and did not jam. I then brought the rifle back to the smith to have it head spaced.
I was with the smith when he head spaced the rifle, and in fact he let me "feel", or push the bolt closed, on the gauge, so I would know what it felt like. It did take two thumbs worth of pressure (he told me to use both thumbs, in fact). The metal pins were of known diameter. To me, they looked like a professional gunsmith set of pins. Definetly not a home made set.
When we found the right size pin it was .268 or .269. Both seemed to close with about the same amount of pressure. So what size locking should would I want?
About the gauge, I think he said no-go, but he may have said go. I can't really remember now, he just mentioned it in passing.
So, my new questions:
1) If it was in fact a no go gauge that was used to check the headspace, then is something wrong? Could he even have head spaced it w/ a no go gauge? He has been doing this for a long time, so I trust him.
2) The "original" headspacing using a fired .308 case....bad idea? Looking back at it, i now thaink that that method of headspacing wouldn't work, but I still don't know much about FAL's or headspacing.
3) Could bad headspacing have caused the rifle to not function? Would that have somehow caused gas pressure to drop?
Thanks for any input. I have not ordered the new locking shoulder yet. I figured I'd wait until we got this hammered out.
Brad