First off use pellets not BB's. BB's are made of steel and when they hit something solid, Like when you miss and hit the steel garbage can behind the model they ricochet....and yes they can put your eye out. Lead pellets are far less likely to ricochet.
Second wear safety glasses, Polycarbonate lenses, marked z87.
Third, co2 will work but it's max velocity with the Crosman powerlets is between 350 to 400 feet per second velocity. You will get about 50 shots per powerlet. (The last 20 will drop in velocity, accuracy will suffer and so will penetration) If you shoot fast the powerlet will ice up and velocity will drop.
Pump or spring piston are the way to go. The guns that take the large air bottles or can be pumped with a bicycle pump or compressor are way expensive. Definitely too expensive for destroying the occasional evil model.
Daisy makes toys don't bother. The Crosman pump rifles and pistols are ok Not great but Ok. If I was going to buy a Crosman I would go with the
1377c pump pistol. It will give you about 600 fps velocity. And you can get a plastic shoulder stock that replaces the grips to make it more stable and accurate.
Avoid the crosman co2 pistols like they have anthrax rubbed on them. They are over priced diecast zinc junk.
If you are interested in a quality co2 repeater pistol look for Gamo. They are priced in the $50 range. Their spring piston rifles are top notch too and they are reasonably priced. They have a few in the $80 range. RWS and Beeman are the Kings of high quality spring piston guns. They start around $150 and go up.
Avoid the chi-com spring piston guns. Many will shoot 30 or 40 shots and crap out and stop cocking. The accuracy is hit or miss also. I really wouldn't trust the safety on these guns either. The problem is they aren't "all" bad. Some are excellent some are poor, the problem is you can have that range of quality from the same manufacturer in the same model. They have no consistent quality control. You really have no idea what you will get. Chinese labor aside, If you can import and sell a spring piston air gun for $35, The price to manufacturer it is in the range of $6 how well can it be made? Remember, It's your health and safety we are talking about here!
If you really want to see massive devastation when you shoot your models get a cheap paintball gun and freeze the paintballs! The accuracy is poor because you have a smooth bore barrel but they will smash the hell out of your model! I saw a cheap paintball gun at sports authority for $25. It uses co2 powerlets and you have to c*ck it every shot.