This is the Model 57 I picked up cheap a couple weeks ago. I noticed it had Unertl-type scope blocks, and that jogged my memory. I had picked up an old Marlin 4X target scope a couple years back at an auction. When it tried it out on the 57, it fit perfectly. I'm not sure who actually made the scope (not sure if Marlin actually manufactured it), but the optics are nice and clear. The 57 & 4X make a nice pair I think.