I think the slot you are referring to has no real use except for manufacturing - since these guns have the receiver & barrel as one piece that slot was made when machining the left side of the chamber for the left side extractor. going in through the side of the receiver is about the only way they could do it. The ejector is a formed sheetmetal piece with what looks like a claw the mounts to the bottom of the receiver..
Thanks Gene, so what looks like a big slot is supposed to be there?
Yes, there is supposed to be a slot on the left side, it's from running a cutting tool in to finish the left side of the chamber, it's the only way they could machine that.
Last edited by GeneB; 01/13/18. Reason: reworded slightly