At one time Federal recommended using their small rifle primers to load .357 magnum with. That was before they came out with magnum pistol primers.
A lot of IPSC shooters use small rifle primers. Sometimes for better ignition of large loads, sometimes to disguise signs of excess pressure in their overloaded .38 Supers.
I found that a small rifle standard primer gave more velocity than small pistol standard in 9mm P, but LESS than small pistol magnum. Are pressures in the same relative proportions? I dunno for sure, but I quit worrying about it.
But I am not telling YOU it is ok. You might do things differently.
