reloading 303 british and case separation

[Leeroy151]

hey y'all,
so, i went to the range with my two Enfields. me and the kid shot both and the latest job i did on the reloads worked better. the cartridges that had been shot in the Savage are a little hard to push into the chamber but otherwise did well. the cartridges shot in the BSA? Enfield chamber in both rifles equally well. accuracy was acceptable to me as a hunting rifle. we didn't shoot at paper, just a gallon jug, freehand at 100 yards. to reload i used 39 grains of IMR 4895, 150 grain FMJ pritsi partisan (sp?) and i neck sized using a Lee die set. last time i used 40 to 42 grains of IMR 4895 and i think that was a bit too much for the cases ran thru the Savage. this go round i didn't have any obvious case separation or swelling. i am thinking about backing off to 38 or maybe 37 grains IMR 4895, cause even at 39 grains the kick was pretty good.
any ideas guys?
thanks,
Lee