In case you missed the OTHER thread - here's what I wrote there - be patient, glasshopper, some of us are LOOOOOONG way from home here.....
I have the sister to this 2" target scope, made by the J [John] Unertl Optical Co, with both the early blued mounts and the later POSA-style alloy mounts shown here. Value in the USA is around $800-1000. THE Unertl maven is Dewayne Greiner. Google his site under Unertl scopes and he'll put you right.
Scopes were made in 1", 1.25", 1.5" and 2" diameter objects, in many different magnifications from x6 up to x36. Mine, made in 1952, is a x18.
As for what it went on, only the x8 version went on the '03, and they are all clearly marked with the property mark of the USMC. If you have such a scope, be warned that there are fakes around - the real deal is worth well-north of $5000 - I've seen one for $12,500, although there WAS a '03 hanging underneath it.
YOU can put it whatever you like - mine is currently on a BSA Martini MkII International, but they are bomb-proof - put it on a centre-fire, as I'm about to on my High Wall, and laff. You'll need the special POSA-style cut-away mounting blocks, BTW, if you don't have them already. Mr Greiner has them, as well as other accessories.
I'm sending a pal here a pic of it installed [sans recoil spring - not needed on a .22LR] so that he can, if he will, post the image for you to see.
tac
PS - Mrs tac has just reminded me that there are also frawks of THIS type of Unertl scope, as put on a replication of the the '03 by the 'Gibbs Rifle Company'. Trust me on this one, they are NO Unertl - the real deal - like mine, is a peerless chunk of optics, even at the age it is. It really is like looking through the very best scope you've ever looked through in your life - .22LR holes are clearly visible at 100m.