I've never run it thru a chrony, reloading data suggests the same as your .300, I just use more powder to get it done. I've tried IMR-7828, RL-25 and retumbo. I use a Fed215 primer and still have unburnt power in the last 5" of the barrel after each shot. Got a steal of a deal on the gun is the only reason I have it, could have bought an identical one in .338 Lapua as well at the same time and didn't, still kicking myself over that one. The Retumbo seemed to burn more complete but was minute of elephant on accuracy. I've used the RL-25 mostly and with excellent accuracy (3/4" or less) with bullets 125gr-200gr. I've got quick access to a chrony now so I need to run some rounds thru it.