Most reports indicate little to no performance differences exist between LPPs and LPMPs in identical loads. There is probably a greater difference among different brands of the same primer type than there is between LP and LPM primers of the same brand. Also, note that the Winchester brand makes no distinction between Standard and Magnum pistol primers. And that is what the Winchester box says. Far too much is made of largely imagined differences between regular and Magnum primers, also, in the case of small primers, differences between SP, SPM, and SR primers. All work fine so long as your handgun will fire them all reliably. Some handguns will not ignite SR and SPM primers reliably, and they should not be used. Of course, SPPsand LPPs should never be used in high pressure rifle loads
I am sure this same nonsense attempt at making primer performance distinctions will continue for as long as there are primers.
Personally, I normally consider SPPs and SRPs as being completely interchangeable, so long as the primer is 100% reliable in the gun. It seems to make absolutely no performance difference regardless of load or powder type. I would throw SPMPs into the mix, except that they are essentially identical to SRPs.