Maybe we are channeling each other brother Rag...
I think about the semi/auto combustions all the time, just not using firing energy only to complete the reload as is your idea. My ideas tend to pursue more external automation to accomplish the task.
I would love to see what you have in mind sometime..
I'm very much a proponent of these things working on all mechanical systems, simply because it's more of a challenge. Unlike some people, who'll give up if something is too hard, I'll give up because it's too easy.
And it's not that surprising that we're working on the same page - I think about just about everything. Yesterday, it was how to modify a particular design of water nozzle for spudgun or firearm use. Didn't quite solve it, but I think it could be done.
The idea behind the nozzle is that it sort of protects the water stream's integrity with a temporary vacuum that's created, to prevent the stream being broken up by air turbulence at the nozzle.
Converting the idea for ballistics could allow muzzle blast to be shaped in a way that would prove more conducive to accuracy.
...and if I can get the idea finished, I'll post the auto combustion idea, yes.