As someone else already mentioned, a chronograph is a great tool to use for working up loads. I try to stick within published data, but I also use my chronograph and closely observe fired cases, as well as how the gun reacts while working up loads. Unfortunately, with plated bullets there's still a severe lack of published data so a chronograph is indispensable in cases such as these as anything else is just a complete shot in the dark. Chronographs are something that may sit around not being used most of the time, but they sure are nice to have on hand when you get the itch to experiment. Sometimes we drop $100 on a nice new set of dies and shell holder but never get around to dropping the same amount on such a useful tool.