Agree that the "real" Reisings are marked. Mine as well are marked. Reportedly some Marlins fit the Reising (I haven't tried that out yet in mine) but I'm looking at the distance between the top of the magazine and the bottom of the bar where the latch would engage. Just guessing on that one. If it's a Marlin, it's an older one. Someone out there must have one of these in their collection. All you .22 shooters chime in so we'll know for sure.