Yeah I agree with you about using romy parts for testing., that spare yugo trunnion and bolt are for my someday .308 build but I'm more leaning toward a 54r yugo with m76 barrel parts and psl bolt and carrier.
If we discover ak (especially yugo) bolts and trunnions can safely handle some high thrust levels then I think I might build my long time idea of a 5.6x57mm ak based system (though that might be best for my m14 reciever )
There are a few ways I can think of testing headspace or atleast locking lug deformation creating a longer headspace, one method I can think of would be adding thin shims to a go gauge maybe like .001 or even .0005 shims but holding them in place might create inaccuracies another method could me micing the distance between the lugs and breech face. My preference though might be a combination of micing the lugs for deformation along with measuring the bolt tail end play, it could be zeroed on part of the trunnion and endplay could be measured with go and no go gauges originally used and thus be a quick way of seeing if the lugs are deforming and the bolt is moving back. Also the breech face could be measured for forward movement of the barrel which I used to think was a non issue untill I had my initial hs problems with my m76.
Maybe we could send bolts and trunnions to zteknik if he's able to use to magflux machine at his work
Sound like decent methods bg? You're right for testing it would be easiest to load rebated rim .308's also I think I can round up a .308 take off though I've also thought a lot about a .243 from reading your threads
I know another way to kill two birds with one stone, like your .308 yugo barrel idea, if I can get enough machine time from my buddy I might buy a psl bolt and try testing with a 54r wildcat, I'm thinking 6.5x54r
Sorry I've been rambling let me know if any of it gives you ideas lol