Rifle Scopes Interesting scope base; any help on an ID?

[WhiteDingo]

I recently came into an unusual 1 piece scope base, and I was hoping you guys might be able to give me an ID.
I'm about 90% sure it's a US Optics product, but an e-mail to them hasn't gotten me anywhere. I say 90% because the clamping mechanism looks just like the mount on my SN4S, and it had a similar vintage USO scope in it.

It's a 60 MOA (yes, 60) 1 piece rail attached base with 30mm rings (that are serial numbered together). That's the easy part. I just can't figure out what rail it's meant to attach to.
I have some ideas, but I'm not finding any rails dimensionally that match. The "trough" as it were measures just over 14mm across, with the recoil stud measuring just under .250"

I want to say it's for a Tikka/Sako style rail, but none of the rails I've measured have matched. Any ideas?

 

[WhiteDingo]

Re: Interesting scope base; any help on an ID?

So no ideas then?

 

[JBW3]

Re: Interesting scope base; any help on an ID?

Not a USO, but I have modified one of these mounts in the past, for the life of me I can't remember who makes this. For some reason I am thinking Armalite.
John III

 

[WhiteDingo]

Re: Interesting scope base; any help on an ID?

Well, that answers that.
If I may ask, what did you modify it for?

Looking at the different versions of the Armalite mounts, it appears that the lower half of the rings and the base are machined as one piece.