I just looked more closely at the last advert (1927?) that Researcher posted. My error was in thinking that the "Riverside" guns were the later 520-30(?) models with the flat-topped receiver. Were the 520-30 guns only produced for the War Department effort? Ok, more close looking at Researcher's last posting. So...the 520A is the flat-topped receiver as well? Whew! Can we now surmise that 520 production ran from 1904 to 1927?

Last edited by Lloyd3; 07/19/13 11:56 AM.