On my MK3 I went cheapo. I bought a BSA Reflex at Midway that was on clearance for $45. It's been going fine for 2 years, .22s aren't that hard on optics. If you want something more substantial, check out the C-More Polymer models. For around $200 they are a lot of optic for the money. I stuck one one a S&W 627, around 8 months and counting. I did have a Burris FastFire 2 on the S&W for a while. Great optic, but I found it hard to pick up quickly under recoil. Though on a .22, it will probably work fine. It works better for me on my CX4 carbine.