Justcurious, The large ring Brno pre-war sporter that I saw here also had the brass plate around the stock wedge exactly as pictured. There would be a need to re-enforce the wood around the wedge hole, so I am thinking it was indeed a factory feature.
Your Peruvian small ring is very similar to the G33/40 except that it also lacks the profile of the left rail which actually makes it look like a large ring action:
John
-------------------- John
"In the Texas Oilfield, everything that does not kill me today, gets another chance tomorrow."