I think there is a fundamental difference between military battle-oriented medicine and that which we all are exposed to. The ballistics of explosion-driven shrapnel and high energy weapons like 7.62 and 5.56 battle rifles are different than those of .38, 9 mm, etc handguns that are seen in civillian gunshot wounds.
In my professional career (since begining residency in 1981), I have never seen a situation in a civillian ER where a tourniquet was necessary or should have been used and was not.
I would not waste space or money on a prefab, one-handed tourniquet, unless you are in the military!!