[ithacaartist]

Ed, the SE-08 Erma system uses the extended right rear feed lip on its mag for an *ejector*, after the standard extractor is removed from the upper. You may not need one if you go with one of these mags. Since the barrel sleeve/adapter is concentric with the bore, your choice of the Erma toggle train with its rim-fire breech block seems appropriate. Your pic of the chamber area makes me think it will need an extractor cut, so I agree with your other friend. Also, there is no feed ramp on your setup. I think one could be welded to its rear, if needed, but you'd need a way to index it unless the insert's position/installation in the bore is permanent.