Went out & tried a short experiment with this today. Loaded up some .357 magnum with a plinking load of Unique (5 gr.) & a 150 gr cast SWC.
Made a few with CCI 450 small rifle magnum & Winchester Small Pistol Primers.
The Small Rifle Magnums were the only ones I have enough surplus of to make it worthwhile for me.
Velocity was close for both. Upper 900’s out of a 4” Python. Two out of three SRM wouldn’t pop double action w/Python. All did if hit single action. All fired fine with a 3” Kimber K6S double action & hit mid 900s.
For me, with small rifle magnum primers in a handgun, not worth it.
While I do have & shoot .357 lever actions, I want the ammo to work in a revolver interchangeably.
For you, using a rifle only & .327 Federal Magnum I’m certain you’re good.
Probably fine with standard rifle primers in handguns too. That 450 is about the thickest cup out there.
