On my 5.56 AR I use an ACOG TA11J-RMR combo, 3.5x35 with a Trijicon RMR with TA51 mount. Great for shooting at a distance or right up close. I bought it because it had a reputation for being indestructible so I figured it would be the only one I'd ever need on that particular AR and I'm sure it will be. My next 5.56 AR will get something a little more affordable lol.