Anything over 400 FPS depending on where it hits you can be lethal. Never point an airgun at another person.
Faster than 1000FPS
Feet per second, referring to how fast a BB pellet travels.
750 fps./BB; 665 fps./pellet The name Power-line may be a little misleading. Modern Pellet rifles are capable of firing a pellet at 1000+ fps. But this is a combination BB and Pellet gun and as far as BB rifles goes 750 fps is a good speed for a BB. This is about as fast as they can possibly go. I own 2 of these and find them very entertaining to shoot for fun.
A BB pellet is only a couple millimeters thick. The pellets are very small. BB's are usually .175 Caliber a regular Air pellet is .177 Caliber
It usually says right on the barrel. Single shot / single load pistols are pellet pistols. Most BB guns have a reservoir for the BB's. There are a few that shoot either a BB or a pellet. You will have to look at the instructions or the display box to see what it says. Pellet pistols are more accurate than BB pistols. Most BB pistols will say .177 BB. Pellet pistols will say .177 Cal and not say BB.
Pellets are faster. BB's top out at around 550 FPS pellets can go a fast as 1,600 FPS (Feet Per Second)
While many pellet guns are configured to be able to fire regular BB's, most BB guns cannot fire standard BB caliber pellets. To fire a pellet, the BB gun would have to be a breech loaded or break-barrel loaded design, and the pellets would have to be loaded single-shot.
bb guns.org
Which model
Pellet guns shoot lead pellets. The advantage of a lead pellet is that it is heavy, and can be shaped into an aerodynamic cone shape that cuts through the air. They are also more responsive to the rifling inside the barrel and spin as they fly. Pellet guns are actually quite different (and much more accurate) than bb guns. You can actually kill small animals with a pellet gun so if you are looking for something that's more of a toy you might want to get an airsoft gun. Those shoot plastic bb's and are non-lethal.
Air rifles use compressed air or C02 to propel the BB or pellet. They do not use gunpowder. Their is no bullet shell and bullet just the BB or pellet.
There are BB guns and there are Pellet guns. BB guns are not as powerful as pellet guns. BB gun can only fire a .175 caliber BB at a maximum of around 500 FPS. Pellet guns can fire a .177 pellet over 1200 FPS. The most powerful class of Pellet guns and Rifles are PCP's (PreCharged Pneumatic) air guns. These require a special pump or Scuba tank to charge them to 3000 PSI and can fire up to a 50 Caliber slug. Capable of bringing down a full size deer. Pellet guns are much more accurate and powerful than BB guns. If you want a powerful BB gun then I suggest a multy pump BB rifle.