How many cartridge does a 12 gauge shotgun carry.
Depends on gauge.
Metal, wire, needles, shotgun bore? What kind of "gauge?" How many kittens in a rainbow?
Yes, they have been made by many companies
Some shells hold up to 15.
Numerous companies in many countries have made single shot 12 gauge shotguns.
None. If you are asking how many pellets, the answer depends on the load. It could be anywher from less than 10 to a couple of hundred.
There are many problems with your question. First there are several different size shot that are considered bird shot. This alone would change the number of pellets. but to add to the problem there is not a standard length. Lengths vary from 2.25 to 3 inches. shot shells are loaded typically by weight until you get to the really large sizes. btw bb is a size of shot typically used to shoot large birds like turkeys.
Most common sizes are .410 bore, 28 gauge, 20 gauge, 16 gauge, 12 gauge and 10 gauge. Note that .410 is the actual bore diameter forward of the chamber. See below for the meaning of gauge. There have been a much wider variety of bore sizes, especially back when muzzle-loading shotguns were common, since a shotgun that does not fire fixed ammunition can essentially have a bore of any size. There have been 8 gauge guns and even larger, mostly used by commercial hunters for killing sitting birds in large numbers. "Gauge," by the way, was originally determined by how many pure lead balls of bore diameter it took to make a pound.
Many different makes, models and designs. Start with Google.
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In fact, many products appear in forms of pellets. They can be used in many fields like animal feed pellets, bedding pellets and home heating pellets,etc.