I had some time today to work on some 300 win mag brass. Got everything ready to the priming step. Cleanened off the bench of everything but priming tool and loading tray with 50 rounds of shiny brass. I reached into the cabinet and identified my Federal GM215 match primers and dumped half the box onto my hand primer. I shook them around and snapped the cover over them. I chucked the first round and squeezed twice and thought...HMMM that was a fairly loose pocket. After a a second shell was primed I decided that this would no doubt be the last loading of this batch of brass and continued on. After about 25 were primed I remembered that this is only the second loading of this brass. Now I was sure something was not quite right. My next thought was....Gee I wonder when they changed the color of these primers? they are not purple. One look at the box on the bench and I relised I just primed a bunch of 300 WM brass with GM155 Match pistol primers. Time to break out the decapper die. DOOH what a time for bad hand eye coordination. I am gonna have to put pistol primers on the other side of the cabinet.