Riss
Member
I started loading up 40 S&W recently and have 4 loads through the Chrony. My velocities are wild, getting differences of 100 fps or better in each loading. Last batch was from 881 to 991 fps. They averaged 917 fps over 22 rounds fired. Not sure if the problem is the used brass, it is fired brass from a range. Cleaned it and sorted it. If bulged or otherwise Glocked it was tossed. I have now seperated 2 different headstamps, *I* and Winchester. Not sure if the case volume or length is different. Possibly some of the brass was already reloaded and stretched. I have checked the press and scale and both are working correctly. All rounds are to spec with OAL a little on the long side but they all check out the same. No apparent variation in the loaded rounds. 5.5 Gr of Power Pistol on an RCBS 550. Anyone have any ideas of what is causing my Chrony readings to be spread wildly ?