bb's are made of steel and must be a loose fit in a smoothbore barrel. Pellets are far more accurate. 

CO2 guns looks like 2 cents a shot for the air (with either the 12 or 88 gram cartridges)

Underlever and sidelever air rifles are nice because the barrel remains fixed in place which imporves accuracy

 

 

Great review of different types of air rifles Link  and wikipedia

Ballistics   air gun ballistics

http://www.germanft.com/BALLISTIKE.html   http://www.velocitypress.com/air_rifle_ballistics.shtml

AirDepot.com review of pellet guns  LINK

Gamo CF-20 Review  LINK  Took 500+ rounds to break in rifle, sound pellets did better than others, a way to decrease the noise

 

How to sight in a pellet gun and another article  velocity explained

For a pellet gun that shoots around 800 f.p.s., I like to sight in at 20 yards for the near distance. The second distance will be around 30 yards, and the pellet will not rise by as much as one pellet diameter at the in-between distances (between 20 and 30 yards). If you sight in at 15 yards with the same gun, the pellet will be back to the intersection of the crosshairs around 40 yards, and it will rise more than an inch in between.

 

Higher velocity means greater accuracy over longer distances so if you are going to be doing any hunting with your air rifle a springer would be the rifle of choice.

Skenco airgun pellets are lead free and contain no tin, precision two piece construction. The plastic skirt creates superior air seal and reduces friction in the barrel. These zinc and aluminum alloy pellets are totally environment friendly. They develop approximately 20% higher velocities than typical lead pellets and penetrate better than any other pellet available in the market today. Unbeatable combination of Quality and Value. Type 1 .177 (4.5 mm) Red Plastic Sabot, Steel Top Made for all standard air guns. When used in air guns rated over 900 feet per second it may go supersonic and start to loose some accuracy. Type 3 pellets DO NOT fit Crosman and Daisy magazines. They DO NOT fit Gamo or Umarex metal magazines:Beretta, Colt, Walther Lever Action Rifle etc http://www.amazon.com/JSB-Predator-177-Grains-Pointed/dp/B001BS98TO/ref=pd_sim_sg_1

 

Daisy M853 Specifications:
The Daisy-Avanti Model 853 Competition Air Rifle is a single-stroke, under-lever cocking single-shot pneumatic air rifle in standard.177 caliber. Cocking force for the pneumatic power plant is 25 lbf. The receiver is diecast, complete with dovetail for scope mounting. The factory rated velocity is 510 ft/sec, yielding a typical muzzle energy of 4.5 ft-lb. Nominal weight for the Daisy Model 853 Air Rifle is 5.5 lbs.

 

There comes a time when a airgun shooter's competitive juices start flowing and expectations move to a new level. Daisy Avanti Air Guns rise to the challenge. From the serious airgun target shooter to the airgun match competitor, the entire Daisy line of super-accurate air rifles and handguns hits the mark with distinction. Simple, efficient design. Superb balance. Tack-driving accuracy that shows up again and again on the medal stand. When you want the very best in an affordable competition air gun, there's only one name to know: Daisy Avanti Competition Air Guns.

 

Air Gun Depot is proud to feature a wide assortment of pellet guns. Pellet guns are specifically designed to fire pellets, as opposed to BBs. Pellets are cylindrical (whereas BBs are spherical) and, when fired, command excellent accuracy for target practice and outstanding penetration and stopping power for hunting. If you are debating between getting a pellet gun or a bb gun ask yourself this question: "Am I going to be doing any pest control or small game hunting with my airgun?" If the answer is yes then a pellet gun is the way to go. If the answer is no then a bb gun should be sufficient for your plinking needs.

The Winchester 1000xs gets a slightly higher velocity (1,000 feet per second); however, it uses a lighter weight pellet to go the distance (.177 caliber). It comes equipped with a 3-9x32 scope and a beautiful walnut stock. It would make a perfect addition to any serious airgunner's collection. Even more impressive than its 305 foot range is its break-barrel design. This makes for faster reloading and automatic cocking, which speeds up time between rounds and decreases the effort it takes to pump the rifle.

For target shooting, choose a .177 cal pellet gun (pellet rifle or pellet pistol) with a somewhat high velocity (at least 500 fps) for shooting up to 10 meters. Spend the exta money on good pellets- it will greatly increase accuracy and consistency! There are adequate hunting pellet rifles and target pellet guns in just about every price range.