I got a prostaff 3x9x40 last year and put it on my 50cal cva optima, so i havent pushed it passed 150, but my observations after about 50 shots with it on are that it is a very clear scope. In low light it is just as good as other 40mm scopes ive tried, in that price range, i have no experiance with any more expensive 40mm scopes so i cant compare it to them. (it does not gather light as well as my 50mm simons, but i didnt expect it too). As far as holding a zero no problems at all so far, i fell while carrying it and checked the zero with no problem. Eye relief is fine with magnum load so you should be ok with any common load. It focuses quite fast once you get it adjusted right. For the money i think its a good scope. I have had no problems yet. jmo.