Ok, I read on a gun forum somewhere that the 9mm pistol is designed to function with a 124gr bullet. Obviously most modern 9mm pistols wont even hiccup with 115, 124, 127, 147 ammo, so that's no really my question. I'm wondering 2 things - one, why is 115 gr ammo cheaper? Two, if I want to run lots of ammo through a HK SP89 or Beretta Storm (blowback operated) - for optimal reliability - am I better off with 124 gr ammo or will 115 be just fine? Ammo would most likely be something on the order of CCI Blazer or WWB - something in the "plinking" category. Defensive ammo of choice is in the 124 and 147 gr category anyway, so I'm wondering about "fun" ammo.
I guess my question boils down to the relationship between bullet weight and the cycling of the bolt in a carbine/SMG style weapon.