The rail detonator gun was ideal for Imperial jumptroopers and their aerial combat maneuvers. The charges could be set to explode on impact, or stick to the point of impact for a few seconds first. An alternate version existed that held heat-seeking properties.
The detonator was known to have been used to a limited extent during the Clone Wars. By the time of Galactic Civil War it was a rarely seen weapon, used only by specialized stormtrooper units, primarily by Imperial jumptroopers. Later it became a popular weapon between the stormtroopers of the Imperial Remnant, which they used to great effect against both Kyle Katarn and Mara Jade.
The rail detonator gun was also used by the men and women serving in Kota's Militia, including the soldiers and saboteurs.
It appears that the texture for the in-game model used for Star Wars: Jedi Knight: Dark Forces II was missing a hole at the end of the firing tube, thus making the firing of a missile seem impossible. Closer inspection of the texture, however, reveals a very small opening for the detonator, though it is much smaller than the actual projectile.