I've been working on a load for my S&W 500 using a 375 grain spire point and Accurate 1680 powder. FPS kept rising until my last batch, it went down. The last two loads were compressed, or pretty close to it. Is this normal?
Also today, testing some 308 loads with benchmark powder the speed quit rising from 38.0 to 39.0 grains...
My method is to chrono 5 shots, delete one wild shot if exists, then average the remaining 4 shots. I don't know if that's a good method, but it seemed reasonable to me.