Working for Leica, who does not make custom cut turrets, I have many customers order from them all of which have been extremely satisfied. They are all replacing our MILRAD based BDC turrets that are already designed for heavy dialing though. They make a very precise product based on the fact that the user actually does their homework on load and atmospherics. I don't have experience with the Viper or any other brand but mine, but would make sure that you do your own chronoing in the conditions that you desire it to be cut in first. Powder burn will certainly vary based on atmospheric conditions (not saying you haven't but just throwing that out there).