Yes calipers, I can't find my inside mics right now, was going to try to find them this afternoon. Sometimes moving stinks still setting up my shop area in the basement bunker.Sounds to me like your receiver is out of spec on the large end by a little bit and your barrel is probably on the low end of spec. FWIW, I miked the take-off barrel I have (admittedly a Target model, so perhaps tighter tolerance to receiver bore) at .686".
ETA: how are you measuring the receiver bore? If you're using calipers, the error direction pretty much guarantees that's the lowest value the actual measurement could be.