It depends on the Model and power source.
Your question is a oxymoron. Pneumatic BB guns are single shot. Machine guns are Multi shot. There are several C02 driven BB machine guns
Yes
A regular BB gun can not shoot air-soft pellets. BB guns shoot a .175 BB. Air guns shoot a much larger 6MM BB.
See the links below.
BB guns (metal BB .177 caliber) fire a projectile that can injure a person and cause an injury. They are not designed to be fired at another person. Airsoft guns fire a large BB (6mm) and are designed to not injure anyone who wears protective clothing and gear.
machine guns, bazooka, canon, shotgun, and BB guns
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.
Canada
If you are asking about Airsoft BB shot in a regular BB gun that shoots metal BB, then the answer is NO. Real BB guns fire at a much higher rate than most Airsoft BB guns. The plastic BB could disintegrate and become flying pieces of Plastic.
Yeah most can depending on the size
Depends on what you mean by "FAR". BB guns are not very accurate beyond 25 feet, although the BB will travel much further. Pellet guns and rifles will travel further and be accurate at a greater distance. This is because BB's are shot from a smooth bore barrel, like a straw, and will tumble as they fly out. Pellets usually use a rifled bore barrel and spin as they are shot out of the barrel. Pellet guns and rifles are usually more powerful than BB guns.
The most powerful BB guns are not really that powerful. However "Pellet guns" are much more powerful. Take a look at the PCP line of airguns at pyramydair.com They use a scuba tank to charge the guns with air. BB guns fire about 350 to 450 feet per second. PCP's can fire well over 1000 feet per second.