I've been working up loads for three different .45 Autos over the past several months and Ramshot ZIP is a real winner among the newer powders.
For some reason, 5.6 grains of ZIP is the most accurate load in two different bullet weights, 200 and 230, across a few different styles - SWC, RN and plated HP. Obviously velocity is higher with the 200 grainers. It still stikes me as unusual that one charge weight works so well like that but the many groups on paper support that conclusion.
It burns about as clean as anything, at .45 Auto pressures you're going to get some soot on your action no matter what powder you use.
It does seem to be about one or two dollars cheaper than other powders which is not a deal killer but certainly a point in its favor.
