New Army "Caliber Configuration Study"

[cory]

...Having said that, my own (non-technical, and probably unrealistic) thought on gun propellant is that the form (if not chemistry) of a typical rocket motor might have advantages: that is, a solid fuel block with a central axial channel which ignites first and then burns outwards until it reaches the case walls. If feasible, this would mean that as the propellant burned outwards so the area exposed for burning would progressively increase, generating more gas and keeping the pressure curve much flatter. It would also minimise the heat transfer to the case and chamber because the burn would not reach the case walls until right at the end. The burning rate could be adjusted by the varying the shape of the axial channel (in rocket motors, the cross-section of the channel is often star-shaped to maximise the initial surface area to provide a boost phase). I suspect that a new shape of cartridge case might be needed for this to work well, though.

Solid rocket propellant to launch a tiny projectile, interesting thought. You could be on to something.