ok, i was thinking about this for a while, what if you were able to make another notch (like the front notch to twist the lug in order to remove it) a little further back on the reciever, my old sheridan had a setup like that. maybe if you put it only in the bottom tube, you could stick something in there to press up on the lug. after you get it out, you can probably get someone with a mill to clean the slot up to look like the front one
*edit
basically add one of these to the back end of the slot
