I don't have any feeler gauges, but the gap on my M69 looks REALLY small, to me. I've wondered if it will be enough to handle temperature variations, etc. I have shot it very little so far, but no problems yet.

I have recently noticed a groove in the top of the frame (just behind the hammer spur, on the left side), not perpendicular, that I hadn't noticed before. More than a "scratch" ... seems like it would have taken quite a blow from a hard steel object to produce it. I guess I'll watch it, to be sure it doesn't start to crack and enlarge. If it's purely cosmetic, I can live with it, but I wish I'd noticed it before I bought it.