i like the FN-P90 for CQ , Even US Secret Service use that SMG that 5.7x28mm bullet can penetrate
and i believe i've seen one before use by PNP-SAF
this is indeed being used by US Secret Service because of its recoil, number of ammos that can be carried, maneuverability, and compact size for CQB. likewise, an added bonus is its ability to penetrate light personal armor such as Level II (like someone will still use such).