so is plastic surgery, teeth, eyes, funerals,Cut me some slack. '74 bolts are rare & expensive nowadays
there is no way you can weld to a bolt and not at least slightly affect the temper around that weld I dont care how small the weld is. that area will be a stress riser and that is were a crack can start. there is no way around it. even if it were retemperd the metal structure will be changed. I persoanly would not risk it. I see K-var is out of 5.45 bolts but they do have 5.56 bolts that could be opend up slightly the extra $50 for a correct bolt is not worth the risk IMOO
CNTRAILRIDER was the bolt pictured from your build?? If it was a blow back how was it attached or locked to the carrier? any picture of the bolt face and the rest of the build?? I would be less concerned of welding on a blow back bolt.