9mm air rifle

That does have some good applications for predator/pest control... but it's power and range are a bit limited. 50 Meters... 70 max? That might be fine for back in the crowded sprawl of The East. But in The West, we need more range. 200 yards. I can accept reduced power... but I need more reach.
Take that system, remove the stocks, fit an HPA tank like for a paintball gun, give it more power, more shots... then we might have something suitable for The West.

Here ya go:
http://www.bigboreairguns.com/07bisonhunt.htm

Now we are talking.

Of course even the very powerful pneumatics aren't going to match a modern cartridge gun for velocity and range. Think of them in the same light as black powder guns, not smokeless guns. I like them because of the low noise-to-power ratio.

The stealth aspect appeals to me as well.
Remember the book FINAL BLACKOUT? The pneumatic machineguns? An interesting idea.

Totally forgot those things. The lack of smoke, flash and softer muzzle blast made it hard for the enemy to pinpoint them with the noise of the regular rifles drowning them out.
Look at this:

That's pretty dang cool right there. I'll have that.

Nah, HERE'S your site Raubritter

http://www.quackenbushairguns.com/