Spud guns with built in pumps?

[Spectrabox]

I always thought having a spud gun with a built in pump would be pretty cool, endless shots without any need for a bicycle pump or air compressor. Anybody ever tried this before? I'd imagine pumping it like a shotgun would be too difficult, but maybe something like a crossbow design where you put it down on the ground with a foothold would work better.

[jrrdw]

Iv'e seen shock pumps mounted below barrels, so yea it's been done. Works well with plinkers that have small chambers.

[dajoro]

Hmm... something like this 3/4" bore-pumped balanced spool valve frozen grape launcher?

[jackssmirkingrevenge]

Here's a nice French project with integrated underbarrel pump.