fuel injected firearm

[keyser-soze at hushmail.com]

>2. Liquid propellant guns (search on that term) are well
>developed for artillary, but I don't know of any light 
>weapons which use this. LPGs are kind of neat in 
>howitzer type applications because (1) A tank of
>propellant & a rack of projectiles takes less space
>than cased solid propellant shells, so you can carry
>more ammo, and (2) you can vary the propellant
>from shot to shot based on emergent conditions. One
>neat hack is 'time on target' in which a series of rounds
>are fired in quick succession, at different elevations and
>propellant load so they all arrive at the target simultaneously.
>(the LPG liquid propellant does not need an added oxidizer).
>
>Peter Trei

Indeed.  See http://yarchive.net/mil/liquid_propellant.html
My ideas were more along the mono-propellent direction using hydrogen peroxide or N-Propyl Nitrate decomposed on a silver/nickel catalyst bed.