I've had good luck with these on .22lr, 9mm, & 7.62x39 SBRs. They see heavy use shooting steel plates, and at ~$65 won't break the bank.
http://smile.amazon.com/Fiber-Optic...psc=1&redirect=true&ref_=od_aui_detailpages00
All but the one on the 7.62x39 (go figure) have eventually shot loose, but its not rocket science to take it apart and put it back together with some Loc-Tite on the threads.
Amazon has other similar "knock offs" but the GRG "brand" seems the best and are the only ones I've purchased. My first one was under $50, but the price seems to be creeping up because they work pretty well and are easy to repair as there is not much to them internally.
I like no batteries/switching and seems to work in any light we can see the targets. There is lame switch and internal LED using really small (and expensive!) batteries, I've never used it for anything, if you do need it to work in the dark then you shouldn't consider this at all. In a pinch it should work if the batteries aren't dead, but I'd not count on it.
Those Primary Arms sights are very good for the money, but they don't look much like an ACOG, and are you willing to spend $250 on a sight for a $300 rifle?
I'd forget about the "RMR-like" small red dot on top, while I've had very good service from cheap tube type red dots, none of the reflex type costing less than the Burris Fastfire II have held up, even on .22lr guns.
Primary Arms is local, and I was one of their early customers back when they were selling their wares at gun shows, so I've tried all the cheap reflex "RMR-type" sights they could get with no success, I believe they have quit trying to find these style and stick with the Fastfire as the "low end" of their offerings.
His main complaint has always been that his direct from China suppliers keep coming back with "we can make it cheaper" he's trying to get the message across "I don't want it cheaper, I want it better for the same price".
, I've seen these at gun shows, they are pretty bad optically.
