Sorry I didn't get back to you earlier. I've been in the Adirondack Mountains the last few days.
The sheath favors a large 2 blade knife. I'd call it "large trapper sized".The Mudbug fits well. The Case Backpocket fits well. The GEC #42 fits well. A GEC #72 fits, but the knife is a bit small for the sheath. A medium Case stockman gets swallowed. A Beer Scout gets swallowed, with just the bail sticking out. A standard scout pattern would be too thick, without a lot of stretching. A Victorinox Pioneer is too small. I think that a Buck 110 might be too big.
Hope this helps.