6mm
BB's for air guns (NOT airsoft) only come in one size .175 commonly referred to as .177 caliber. If you want to know about airsoft BB's then you need to put the question in the "Airsoft category."
6mm
probably not... the bb size has to be the same caliber as the bb gun. the airsoft bb is also made of plastic so it would probably shatter inside of the barrel because it is too light.
yes, most green airsoft bb's are biodigradable
No. Metal bb's will not work in airsoft guns.
It's uses size .12 for best results.
bb
Yes, the only difference is their weight.
A bb (as in a bb gun) is a small plastic pellet fired out of a gun (sometimes known as airsoft guns)
If you are talking about airsoft bb's, then yes. Most bb's fall between .12 grams and .30 grams, and a 20 gram airsoft bb wouldn't work well.
almost every gun for airsoft uses a 6mm (milimeter) BB. try that.
If you are asking about traditional BB guns, Not Airsoft. Then the answer is basically one size .177 Cal. At one time the BB's were .175 Cal but that was in the past and the difference is so minimal that it does not matter. Today's BB are made from Steel, Copper coated or Lead. One Size Fits All.