What does this peep site fit?

[wd113]

I have this Williams site I picked up somewhere along the way, and am trying to figure out what it fits. The profile seems to match something like a A5 or old stevens 520 shotgun. Can't think of a rifle that would have that profile off hand. Any one have a guess???? Thanks!

 

[MadDog]

Remington model 8 or 81.

 

[wd113]

Thank you..... Looks like a pretty rare one (the rifle). Into the 'doubt I'll ever use this box' it goes....