The larger receiver ring wasn't an issue since they were purpose built barrels made by Steyr. They just followed the basic contours of the M1903 barrel....but weren't M1903 barrels.

I have heard of, but not seen Russian conversions to 7.62x54 of Turk Peabody-Martinis. Russiaicon captured a fair number of these in their original chamber. During WWI everyone was converting available BP rifles to their standard smokeless rounds and I see no reason to think Russia didn't as well....because they certainly converted Berdan II rifles to 7.62x54. Considering the large number of Berdan II conversions done and the very few that have surfaced in collections, any similar official conversions on a much smaller scale would indeed be rare.

While a fair push for the action, this same design of course was widely converted by the Brits to .303, so in theory it would work. The main variable here is metalurgy and frankly I don't know whether the Providence Tool production steel was as good as the Brit steel of the era. Many if not most of the Turk conversions to 7.65mm had a rather peculiar reinforcement to the frame, so Steyr at least thought it warranted. Detailed pics of a 7.62x54 conversion would be much appreciated.