[Unclenick]

NavyLT,

That really applies only to pistol primers. Some standard pistol primers have thinner cups than the pistol magnum primers. That came about because the difference in peak pressure between magnum and standard handgun rounds can be well over 300%. Many older handguns and especially tuned handguns for match loads can make weaker firing pin strikes than standard, and don't fire hard primers reliably and so require the standard ones.

In rifle primers, that huge pressure difference does not occur. The rifle magnums get their extra push mainly from capacity for a larger quantity of a slower powder, and, with only a few exceptions, their peak pressures are generally within 10-20% of standard round pressures. As a result, you don't need a heavier primer cup to withstand their peak pressure.

The exceptions among rifle primers are the extra hard CCI #34 and #41 primers made for use in military-style rifles with floating firing pins. Those have harder cups than other commercial primers. They are also magnum strength, as they are a civilian version of military primers that just have not been put through all the mil-spec certifications, AFAIK.

Nick