I am in the market for a ier/scout scope to mount on a .500 s&w handi. My choice was the leupold FX-II 2.5x28. While browsing trying to find the best price I came across a nib old stock M8 2.5x28 for about $50 less. Apparently this model has been discontinued. The specs that I can find are very similar between the two. Does anyone know the difference in these models? Thanks for you help.