I just bought my first ever air gun, it is a Crosman 2240 air pistol. .22 caliber, single shot, uses Co2 cartridges. How many shots is a typical Co2 cylinder good for? It didnt say in the owners manual. Will I gradually lose velocity as the Co2 cylinder is depleted, or will it just quit working all at once? I bought the gun because my next door neighbor has had several thousand dollars worth of damage done to his siding by a couple of woodpeckers and I plan on killing both of them before they decide to start in on my house!