rem 1&1/2 vs rem 5&1/2, being disatisfied with all forum answers about a year ago, i call rem factory, and got this answer. NO change in
power, just cup thickness. they use 5&1/2 for factory loaded 357 sig and 40 S&W to prevent flow-back into the firing pin opening. i use it for everything including 38spl & 380 with no problems. they said it is NOT a magnum primer.

john