savage M1's and M1A1's have the "Full Auto" phrase on 2 lines...whereas, the Bridgeport guns have it on a single line. that's the quickest way to tell on the frame. on the receiver the quick way to tell is by the inspector...GHD inspected bridgport M1A1 factory guns, where as RLB then FJA inspected the M1/M1A1 savage guns. i'm not exactly sure when the inspector's changed over from RLB to FJA, my gun is 78,7xx and is FJA inspected. if I remember correctly all the M1's where made by savage. as the Bridgeport made guns had trouble passing the cycle rate test in the M1 timeframe...or at least, the inspector was pickier on cycle rate. by the time Bridgeport guns where passing inspection, the M1A1 alteration was in effect and the Bridgeport made guns where update with the A1 updates. this may make it sound like I know what i'm talking about...but in reality, I read this in Frank's book. hopefully I am remembering correctly.