Not sure but would not the 300 BO with a 110 grain barnes penetrate more "stuff" than a 124 grain HST from a 9mm carbine?
Not even close. Pistols cartridges (9mm/357/40/45/etc) are literally the worst at penetration of indoor structures while also having the smallest wound channel.
Once again- pistol caliber carbines SUCK for real use. There is nothing you can dream up to take the stench away from that.
And again, increasing velocity on pistol bullets DOES NOT increase performance. It DECREAES performance. Modern pistol bullets are designed to perform exactly at their correct velocity window. Adding FPS hurts them.
While our military has mostly moved away from smg's, the Tommy Gun and Grease Gun seemed to have worked pretty well in WWII.
Because they didn't have anything better. There is not one that would pick a SMG over a M4 based 5.56 or 300BO. And as soon as they had the early 5.56 carbines they dumped the SMG's immediately.
A super sonic 300BO or 5.56 with a can will be fine without ear pro if needed for its purpose and has the rather not insignificant benefit of better tissue damage, less risk of over penetration, better platform, etc, etc, etc.
