Receiver doesn’t fit frame

[Fadedkrill]

Hello, just today I got some 1928a1 receiver pieces from Bridgeport28a1 (thank you again btw). Now while I was inspecting them with my frame, the rear piece didn’t seem to go all the way. My theory is that it’s the frame’s fault, it’s some repro aluminum frame I bought for cheap at Numrich, maybe has to do with the inner rails but I have no clue. Any help could be appreciated.

[SparksNArcs]

If it's an aluminum frame it's going to be from a M1927A1 Lightweight model repro Thompson. Is there a hole for the fire selector paddle? If there isn't, the frame is meant for semi-auto only receivers, and the rails at the end stop short of original Auto-Ordnance specs to prevent an original receiver from sliding on.

[Fadedkrill]

1 hour ago, SparksNArcs said:

If it's an aluminum frame it's going to be from a M1927A1 Lightweight model repro Thompson. Is there a hole for the fire selector paddle? If there isn't, the frame is meant for semi-auto only receivers, and the rails at the end stop short of original Auto-Ordnance specs to prevent an original receiver from sliding on.

well I was able to put the parts for a full auto frame, this new information makes me think the brochachos at Numrich took some of those semi auto ones and drilled it out, guess they forgot about the rail but I can’t confirm, when I bought it was in the 1928 section

[SparksNArcs]

That frame has the cutback section above the magazine rib slot. It's a Kahr frame that's been modified. You can either mill off the rails on the rear piece of the receiver until it lines up, or mill the frame slots back further; the former option is easier with basic tools.

Edited June 16, 2024 by SparksNArcs

[Fadedkrill]

3 hours ago, SparksNArcs said:

That frame has the cutback section above the magazine rib slot. It's a Kahr frame that's been modified. You can either mill off the rails on the rear piece of the receiver until it lines up, or mill the frame slots back further; the former option is easier with basic tools.

If I did the former, how would you recommend me to do it, and would it affect the way the gun works since I’m planning it to make it a semi build

[SparksNArcs]

An angle grinder with a cutting disc could be used to remove just enough of the rails on the rear receiver chunk to get it to fit correctly. It will not impede making it semi, and actually is intended as a denial to prevent an unaltered full-auto receiver from being attached.