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?
38.5gr 1236
40.0gr 1337
40.9gr 1360
41.5gr 1351
Also today, testing some 308 loads with benchmark powder the speed quit rising from 38.0 to 39.0 grains...
36.1 2233
37.0 2264
38.0 2381
39.0 2382
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.