It is difficult to find even 10 gauge shotgun ammo today. I have my doubts if 8 gauge shotgun ammo is even made any more, but corrections welcomed.
Remington makes a industrial 8 gauge kiln gun.
A person is able to buy a 12 gauge shotgun in a gun's store or a store where equipment for hunting is sold. One may also buy a shotgun in an exibition show where the law permit it.
Yes, it is larger, the smaller the gauge the larger the bore i.e. 3 gauge is larger in diameter than a 8 gauge or a 12 gauge.
Market or kiln gun
Federal law says 18
Yes. The Mossberg 500A1 is a .12 gauge shotgun.
mossberg makes a pink shot gun, and remmington makes a 20gauge pink shotgun