You will have to experiment by shooting as many different types as you can find/afford. Weapons exhibit preferences for certain weights/brands.
No. They will not fit. Trying to force a pellet of an incorrect caliber into an airgun can break it and potentially hurt the user.
It depends on your definition of Airgun. Are you asking about Air Soft or Pellet gun? The strongest Pellet guns are in the PCP ( Pre Charges Pneumatic ) class of air guns. These require a scuba tank to charge them to 2000 to 3000 PSI and can fire up to a 50 caliber pellet.
If you are talking about a .177 caliber pellet. Most likely the answer is NO. But if you are talking about a 45 caliber or 50 caliber pellet then the answer is Yes. Pellet guns come in .177, .20, .22, .25, 9MM, 45 cal and 50 Caliber. The last 3 sizes are fired by PCP air rifles (Recharged pneumatic ) that require a scuba tank to charge them to 3000 PSI. They are still pellet rifles just the BIG BOY of pellet rifles.
It all depends on the model, Pellet size and power of the airgun. Most are capable of shooting small rodents and game. Like birds. However high end pellet rifles that are in the PCP class ( PreCharged Pneumatic) air rifles are capable of bringing down big game like a moose. These air guns & rifles can be charged to 3000 PSI and can fire a 50 Caliber pellet.
It depends on the size, weight and FPS of the pellet.
What kind of pellet guns? Airsoft or airgun? Either way, you don't need to have a license. For an airgun, i think you just need to register from the store you bought from.
Of all the different power plants. Spring, Nitro, C02, and Pump. PCP is the most powerful. They may not be the fastest but they carry the hardest hitting pellet of all the airguns and rifles. PCP can be charged to 3000 PSI. A normal 12 gram C02 puts out around 800 PSI. The largest Pellet, any of the other air systems is capable of, is a 25 caliber pellet. ( and that is in very few models) PCP's can fire 9 MM, 45 Caliber and 50 Caliber pellets that out weigh any airgun pellet. These are also the most expensive and accurate airguns. PCP's are used in Olympic matches all over the world. A large Caliber PCP can bring down a moose, No normal airgun can accomplish that.
If you are talking about a PCP (PreCharged Pneumatic) rifle. With a .45 caliber pellet, then "Yes" It can. I don't believe there is a 40 Caliber pellet gun.
No. a 177 is a 4.5mm pellet. A 5mm is a 20 cal pellet. A 5.5mm is a 22 cal pellet Don't try it in the wrong airgun.
Normally (NO) but it is possible if the circumstances are right. Most airguns, not Air Soft Guns, fall into the ,177 pellet or BB range. However pellet airguns do go up into the 9MM, 45 Cal and 50 Caliber barrels and pellets that are capable of killing someone.
How small is small? You will need a larger caliber. Something like .25 cal. Also suggest you get a rifle not an gun. Select a hunting pellet (hollow point) with a much heaver grain. Hogs have thick skulls.
The 620 is a 4.5mm or .177 caliber pellet rifle and is rated around 450 FPS.