If i could add a note to this, and please don't think i'm butting in Dustin, it's just a little extra note to bear in mind.

SMG's in the modern era are used more in the urban setting precisely for their lack of penetration.

I'll explain. The SAS will use SMG's in hostage situations because bullets wont accidentally OVER penetrate a body or wall. If you imagine using a rifle in a house, the 5.56 or 7.62 rounds could easily penetrate a wall of and enemy combatants body and those stray bullets could well end up killing civilians and the hostages and in most situations the forces attempting the rescue don't know where they are being held exactly. This is also a benefit with room clearing as friendly forces may well be in an adjacent room and vulnerable to unchecked fire penetrating walls.

Just an little thing i thought i would add as the negativity of the pistol cartridge being used can be turned to a great advantage in the right situation.

~Tsardel~

__________________
Inquisitor Lord Fyodor Karamazov
"There is no such thing as a plea of innocence in my court. A plea of innocence is guilty of wasting my time. Guilty!"