I agree with FAL308. The pistol caliber submachine gun is obsolete as a general issue military weapon. One of the main reasons the M4 was initially looked at was to replace the .45 grease gun that is a basic issue item on every armored combat vehicle. With the MP5 already in the system and ammunition comptability with the M9 pistol, it would have been very easy for the US to stay with a sub gun if we desired. I think the submachine gun is all but dead. It's last holdout will be as a personal defensive weapon for aircrews, but I predict the M4 or similar weapon will replace it in that role too. Small quantities of submachineguns in special ops units will be all we see.