Seems about an average price to me for GB listings, which are usually on the high side.  The standard Lyman 48J had a slide graduated to 75, so don’t know what to make of this one, except that the owner had long-range ambitions!  Do the base & slide ser. numbers match? 

Have you inspected for the locking lug hairline crack, which the pre-A models sometimes show?  Doesn’t effect shooting, but should lower value slightly.  Still, a very clean 52.

rwsem said
I haven’t seen it in hand- offered for sale by an out of state gun store and they didn’t pull the receiver sight off for me…. I’ll ask about the wood- I wasn’t aware of that common occurrence.  

They don’t have to do anything more complicated than push in the slide release button, pull out the slide, & compare the numbers on the base & back of the slide; might be a special-order sight, or a mis-match.  The hairline crack would be in the front corner of the rcvr locking lug, though this gun shows so little use I doubt it would have happened; probably not worth worrying about.  

rwsem said

Update: sight and base match- X63 on both.  

Since the regular slide has, according to the catalog, “plenty” of elevation for shooting at 200 yds, the slide on this one would stretch that to who knows what…500 yds at least, 1000 yds perhaps? Were there any RF matches shot at that range?   Would be interesting to know the original owner’s intentions.  Though there’s nothing special about the rifle itself, I think this sight makes it very special.

By the way, I shoot regularly at 150 yds, the max range at my club, which requires a trajectory so high that the bullet completely misses steel targets at 50 & 100 yds.  Therefore, imagine the trajectory of a bullet fired at the max elevation of this sight!  Would be coming down like a mortar shell.