Got my other parts,including the semi trunion. The trunions measure about the same at the rear,ID .710 FA,712 SA. The front of the SA is .040 smaller ID than the FA. So for an experiment I made a shim from some .020 steel I had laying around, put it between the bbl and FA trunion and it works. Fits nice and snug with just a smidge of wiggle, a little less wiggle than the SA trunion. Both lock in tight when the bbl nut is tightened. Just FYI if someone wants to use the FA trunion. It wont count as a 922r but if you soldered the shim in I think it would be legal-just my opinion. BTW- does anyone need an FA trunion w/ shim? I just happen to have one!
P.S.-See the numbers? The shim is a cheap SS ruler fron Harbor Freight!