I have experience with 5 of the 6-18X40 Nikon Buckmasters. 3 of them mine and 2 belong to friends. I have seen these scopes on 17HMR, 222 Rem, 270WSM, 7mm-08, 7mm STW, 300WM and possibly a few others. 2 of mine are the older AO model, and the other is a side focus. My friends have one of each. When my buddy first started shooting his AO model he experienced about a half dozen rounds that the scope didn't track when it was adjusted. Just every now and again. That problem healed up pretty quickly (burr?). Other than that everything else has been favorable. When I purchased mine they were discontinuing the AO model and I picked them up just under $250 each. So I figured what the heck! And then about a year later they had a sale to get rid of a bunch of demos and the new model went on sale for about $260, so I bought another. I will say I prefer my Leupolds and certainly trust them more than the Buckmasters. But so far the Bmasters haven't given me a bit of trouble.