Personnel in Britain's Ministry of Defence (MoD) do know how to use a submachine gun.
Although, it seems they have a little trouble holding on to them while on the water.
Responding to a Freedom of Information request, the MoD admitted that a submachine gun "fell overboard" last year. Specifically, somebody dropped the Heckler and Koch MP5 rifle over the side of a boat. MoD didn't offer up any more details.
Most likely the submachine gun went overboard during operations around naval bases in Portsmouth, Plymouth, and on the River Clyde near Glasgow. MoD uses a fleet of inflatable and normal vessels in these areas.
But the MoD isn't alone when it comes to lost firearms.
The British Army lost nine weapons in the 2016-17 financial year detailed in the Freedom of Information request report.
The army had seven weapons (four .22 bold-action biathalon rifles and three .22 Anschutz biathalon rifles) stolen from vehicles in Sweden.
A Glock 17 pistol was lost at some point during an army operation.
The army even lost a standard-issue SA80 rifle in the water during an exercise in Brunei.
Rounds were also stolen, including 41 live rounds and 300 blanks.