Trying to fix old sears jc higgins 12 gu for friend. Put shrll into mag, it kicks back out and jams against floor plate. Anybody?

Are the shell stops functioning? (Are all the parts intact? I.E. Did you check against a parts schematic?) What's the "floor plate?" Do you mean the carrier?

Yes, the metal plate that covers the bottom of ejection port. All parts appeR intact.

Try posting a photo or two. This should be a High Standard pump.

Its a semi

Pics tomorrow

Should be a High Standard Model 60 then. Check the cartridge stops and carrier mounted in the frame that are held in by small vertical pins and wire spring clips. Something is either missing, bent or broken.

Cartridge stops. Thanks.