Marlin .410 with an interesting feature

Well, I did it again. I was looking for a .410 shotgun for small game hunting, and every shop I went to didn't have anything I wanted or fit me, so I looked around online at places I had bought from before, and found an original Marlin .410 lever action shotgun. This one being a deluxe model, however it seems to have an interesting feature I've never seen on one before. It looks as though someone added a button to the bottom of the frame, and I am wondering if it's maybe a magazine cut off. Someone had taken the time once to add ivory inlays to the already deluxe version and I am wondering if that's when they added this. I got the gun at a shooter price so it could be an interesting modification. I included photos of two other Marlin .410's to show what they look like normally. Anyone else ever run across something like this? I am still waiting on the gun to get here to see for sure, but it was professionally done from appearances and a long time ago from the wear on the gun.

So it is not another takedown creation with a different design approach? It favors the trapper takedown you found. If not then I would look at the possibility of it being a way to empty the magazine all at once without cycling the action for each round.

I don't know, but that's very cool!

Marlin made the 410 Lever guns back in the 30s-40s off the top of my head, all that I have looked at are not checkered & I have not seen the button before either. Good guns & fun to shoot, they are on the rare side for the old ones. Marlin & Winchester along with a few other makers started making them again a few years back.
J/S