I think shortening a +2" gas system from 26" to 20" already counts as a "non-reversible mod". LOL.
Yeah...there's that...
I don't have a problem with chopping the barrel or drilling out the gas port... talking about the choice of test ammo.
Just sayin that I would set-up the rifle for ammo that was in spec and not worry about whether it fires the worst ammo that one can find. Lacquered cases can tend to stick to chamber walls.
That's likely a better than decent barrel and would shoot real well with good ammo.
