Get a pellet rifle. Air shotguns are a joke, no matter who makes them. Air guns just don't have that much energy anyway, let alone when you spread it out all over the place between a bunch of shot.

Get a 1000+ fps air rifle and a decent little air rifle (or rimfire) scope, and start shooting. The single pump models will give you a lot more energy than the 10 pump models, but (don't tell my mom) one thing I liked about my 10 pump jobs when I was a kid was that I could only pump it ONE TIME and set up green army men in my bedroom and "work on my shooting skills" playing marine sniper... (that reminds me.... where do you buy green army men these days? haha)

Also, stay away from that "air ram" crap that gamo is pushing these days. If it really worked, yeah, it'd be great, but the durability and reliability on those tubes is terrible right now. It's cheaper for them to make, and it's a new selling point, but it's kinda like airbags, it sounds good, but it isn't really any better.