Extremely Short Barreled .223s
Please remember that there is a velocity trade~off for those really short barreled nifty .233 "pistols" that are neither pistol nor rifle & I suspect cannot function as either too very well.
The critical minimum velocity for obtaining maximum terminal performance from .223 Remington/5.56mm ammunition is approximately 2700 fps.
Bullets that are propelled below this velocity do not provide optimal terminal performance, and thus are less capable of creating wound trauma that will produce rapid incapacitation of a criminal attacker.