[arcticap]

I'm not sure why the harmonica feed mechanism would need to be dependent on recoil energy to operate the mechanics of its movement.
For instance why not just rely on battery power and/or a micro processor program turning some gears to move the harmonica "magazine" along?
Or something like a solenoid or another method that hasn't been considered?
Could the firing pin be operated by an electromagnetic switch or relay?
Or why not use an electrode to ignite the powder rather than percussion caps?
It just seems that the basic method to achieve the concept could be updated by using newer technology which could make the project more feasible, if not more interesting.
There may be more than one way to make the concept work besides trying to harness recoil energy by capturing it with a mechanical design.
Ask 10 students or 10 design teams to build a new type of gun and 10 different designs may be produced that will accomplish the same result.
In that way various types of engineering students may even be interested in working on such a project and would be free to come up with their own unique ideas and designs about how to best accomplish it.