An excellent suggestion if the ultimate aim for the weapon is meat for the pot or maybe some intermediate range sniping. I'm afraid that the pace of modern warfare demands a rate of fire unsustainable by an externally pressurized gas system.
Let's suppose a rate of one shot per second for thirty seconds. How big must the gas reservoir be to maintain that rate while maintaining a pressure high enough so as not to affect point of aim? How long would it take to restore the reservoir to full pressure with a hand pump?
A reasonable answer to these questions will define a practical combat weapon. If, however, the reservoir is the size of a brace of scuba tanks and takes and hour to recharge I would question its utility.
A spring/piston design is essentially a single shot and would suffice for hunting. A design of either type that minimizes muzzle report and was reasonably compact would be useful to eliminate pests without waking up the neighbors.
Regards,
GtG
I would look into some high end portable framing guns, they use a butane cartridge and a combustion chamber, up the pressures say by using acetylene gas and oxygen....?
I used to have a carbide cannon when I was younger.
Even if the feds swooped down and took ALL primers off the market there are other ways to work around or to advance, and thats the goal to advance.