Rifle Scopes Stupid Question...

oneshot onekill

Gunny Sergeant
Full Member
Minuteman
Jul 29, 2008
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DeBary, Florida
What goes on that???... (Besides the oil I already put on those threads to stop the rust!)
35hr7a1.jpg

It's on a Police trade-in rifle I recently picked up. It appears to be the mount for some sort of Laser designator or something but it looks "Brand Specific" to me and I was wondering if anyone here knows the brand... or if I'm even right about what goes on it. I'd like to maybe buy the accessory that's supposed to go there. Thanks in advance guys!