BB basically only come in one size .177 or .175 to be exact. Pellets come in different sizes. I can only think of one model Air pistol that requires special BB's and that a Gamo P-23 it requires led BB's because it has a rifled barrel and steel BB can damage the barrel.
.12 gram bbs.
Depends on the FPS. If the gun is over 400 fps it can go threw a can. My friend has a 400 fps ak 47 and it can kill the can.
Light .18 gram bbs.
400 fps
it depends how much FPS (feet per second) your gun has. If it is at least 350+ FPS then i would go with the 8mm anything below that and the BB could break and jam your gun. But if u have a shot gun use 8mm. now this is for AIR SOFT GUNSFor BB guns, it still depends on the FPS but the BB wont break its just your accuracy wont be as well higher power should always use 8mm if its 450+ FPS
For a spring gun, a normal fps would be from 200-280 For an electric gun, a normal fps would be from 300-400 For a gas gun, a normal fps would be from 300-500
Depending on the FPS and the thickness of the Styrofoam, possibly, but normally no.
The fps of a paintball gun is usually in-between 300-400
What 0.5? If you mean the force, 0.5 joules for an airsoft gun is average. If you mean the weight of the BBs, its depend on the speed (fps) of the BB. 0.5 gr BBs is very uncommon/rare.
A good FPS (Feet Per Second) for an airsoft gun depends on where you will be playing. Typically, FPS between 300-400 is suitable for indoor play, while 400-500 FPS is better for outdoor fields. Check with your local field regulations for specific guidelines.
It all depends on what you mean by "protect" A jacket should keep you from feeling anything below 300 fps at all, and will allow you to only feel a slight sting for anything under 400 fps. 400-450 fps might start causing welts though.
No. Aspects which determine how powerful an airsoft gun is actually it's spring (stronger/harder the spring means bigger fps), compression (better compression = better fps), and weight of the BBs we use (heavier BBs in the same fps can deliver bigger energy).Edit: If a gun that is automatic in real life is spring and very inexpensive, it is probably cheaply made and therefore almost definitely weak. However, "manual" guns that are spring are usually at least fairly powerful, such as bolt action sniper rifles.