I'm looking at the inside of my 1937 Mauser and I can't even see the edges...It's like the inside was machined after the holes were drilled...Or they're not through-holes...
Edit: My 1900AE has the staple legs showing on the inside, so the holes
are through-holes...And the AE shows grind marks on the staple 'legs' from after the machining of the inside...