No, that protrusion of metal slides into a small groove on the Ace receiver blocks. Look at http://riflestocks.com/AKStampedModsRequired.htm and you can see the small grove on the back of the AK receiver block. I suppose if you are going to have a back plate welded on, like the tromix one, you may have to remove the protrusion. Shouldn't take too long with a bench grinder or dremel, but would be a pita to do with just a hand file. Had to make a similar mod with my current project...now if I could just find time to finish it.