Joe,
Older Marlin carbines had the front dovetailed & dressed up so it looked like one piece. This ones a second variation I believe. The earliesat had a block dovetailed like this with a blade pinned into a slot. This is a pre ww1 1894 barrel
![Image](http://i11.photobucket.com/albums/a186/Leverdude/Gun%20pics/100_2808.jpg)
A carbine would have a sight real close to this, its now mounted on the gun pictured above. Only problem is theres zero elevation adjustments. I'v been fileing it down but its still high, getting closeer tho.
This is a repro Marbles similar to those found on some old Marins, I believe its off a Cowboy model,
They used front sights like this alot, mostly on Rifles tho I think. Least every gun I'v run across with one was a rifle, I'm speaking of the front sight on the upside down gun.
Heres a not so good pic of the sight that came with that gun. Its a semi buckhorn missing the elevator. I have one that fits but dont think its correct. I believe its a Rocky mtn sight & should have a harpoon type elevator.
If you look carefully at the first picture of the upsidedown 93 you can see iit wears a reciever sight. Its known as a Hepburn sight & the gun came driled & tapped for it. I took it off when I found an elevator for the original but might put it back.
Anyway, hope this helps even a little.