[Ultra Tech] Variable Solid Propellant Firearm

[Varyon]

I guess I'm on a bit of a UT gun kick at the moment. Over in my thread about increasing firearm power with TL, Anthony suggested modern smokeless powders may be at or near the maximum specific energy for a stable monopropellant. I'm not sure I buy that, but it got me thinking about options to simply add more propellant without calling for long cartridges, and I thought of this monstrosity.

The idea is that, as with a liquid propellant firearm, you have a magazine of bullets and a bottle of propellant - but instead of the bottle consisting of two chambers with separate liquids (mixed and injected into the firing chamber just before shooting), it's instead filled with smokeless powder. You set how much you want to use, it dumps that amount in the firing chamber, and the bullet is loaded in and then pressed back to basically pack down the powder (if necessary; I think modern cartridges typically have the powder loose in there, so maybe you could just leave the powder loose in the firing chamber). The powder is then ignited (by electricity, or by a percussion/blasting cap of some flavor that is loaded in from a magazine when the bullet is, but on the opposite end of the chamber), propelling the bullet with the force you dialed in earlier.

This would give you the variable performance of LP (so you can use suppressed shots against close/unarmored targets, both making less noise and conserving propellant; use extra propellant to boost your performance against distant/armored targets; or use the nominal amount of propellant for those in between) without needing to worry about mixing issues (from what I understand, one of the big hurdles for LP is the random formation of air bubbles when mixing the liquids together, which makes performance too variable from shot to shot to have any degree of accuracy). It also gets you the enhanced magazine size of LP, as your magazine contains only the bullets and you've got a separate propellant bottle. And, if you need a really powerful shot (and your weapon is up to it), you can potentially have more propellant than what a standard-sized cartridge could hold.

Does this sound potentially feasible? I wouldn't expect this to be able to manage a very high RoF - maybe full auto isn't an option, and such weapons can only have up to RoF 3? I'm thinking the same statistics as LP would probably work (it should probably be cheaper than LP, but I'm not sure a mere +50% is sufficient for LP anyway, even if the latter becomes workable); indeed, there probably wouldn't be much need for these weapons in a setting where LP is an option.