OK so I have a Marlin 512 12 gauge slug rifle. I was wondering if anyone has tried these skinner barrel mounted peep sights with the removable aperture so you would have a ghost ring for hunting or a peep sight for target work. Do these work for you all? I was hoping to put a fiberoptic sight on the front ramp. The Marlin 512 has the same sights as a marlin 336. I compared both of my marlins both made in mid 1990s.