If that's the part I think it is then you're right. It's part 21 cartridge stop plunger. Looks like it goes into the receiver near the front of the trigger. So when you rotate the action and pull it will act on the magazine to keep excess cartridges from coming out.
Hope this helps.
If you've got one foot in yesterday, and the other in tomorrow, than you're pissing on today.
Last edited by GrtWhytHype; 04-02-2013 at 12:27 PM.
Reason: Piss poor information