Parts for an American Gun Company shotgun will only be found as part of another shotgun. Haunt the local gunshows for one that is being parted-out. As for the gauge (not caliber), did you mean "bigger than a 410"? There have been 24, 28, and 32 gauge shotguns made. Of these, only the 28 is still available in the US, but I believe 32 gauge shells may still be commercially loaded in Europe.
smaller the number, the smaller the caliber.
Written as .16 caliber (notice the decimal point?), that would be a VERY tiny bullet- .16 inches in diameter. That is smaller than a metal BB- which is between .17 and .18 inches. Written as 16 caliber (no decimal point) it would refer to the length of a cannon barrel- 16 times longer than it is wide. But you may have caliber confused with gauge- shotgun shell sizes are usually given in gauges. A 16 GAUGE shotgun is about .69 caliber- or .69 inches across the shell. They are smaller than a 12 gauge, bigger than a 20 gauge (with gauge, smaller number means bigger)
There is no "30 guage" firearm. The term Gauge is used to denote the diameter of a shotgun barrel- the smaller the number, the larger the barrel. Rifles and handguns are denoted in calibers- caliber being one inch, and expressed as decimal fractions in 1/100th of an inch. If you are trying to compare a 20 gauge shotgun to a .30 caliber rifle, the 20 guage is about .690 caliber, versus .308 caliber for the rifle. Shotgun is much gigger in this case. But if there were a 30 gauge, the 20 gauge would be larger.
9mm is roughly .35 caliber, .32 caliber is slightly smaller, 3 hundredths of an inch smaller, in diameter.
No. The AK-47 fires the 7.62x39mm round, which is of the .30 caliber, smaller than the .45 caliber.
.61 Caliber is the same as 20 gauge. Rifles are generally measured in caliber which is expressed as bore diameter. A .44 magnum means a .44 inch bore; similarly countries with the metric system use metric bore measurements (ie. 9mm Luger) Shotgun measurements are expressed in gauges. Gauge measurements are fractions of a 1 pound ball of lead. A one gauge shotgun shoots a one pound ball of lead. A 12 gauge takes 12 round lead balls to equal a pound and a 10 gauge equals a tenth of a pound. The smaller the gauge; the larger the bore. The only shotgun I am aware of that is measured differently is the .410 shotgun which is approximately .45 caliber or a 67.62 gauge.
.223
32 caliber is a little smaller then the 38 caliber
Either platform can be larger than the other. The 45 has the larger projectile. Caliber is defined as the diameter in fractions of an inch, so .40 caliber is smaller in diameter than .45 caliber. Caliber can also be defined in the metric system, measured in milimeters. The .40 caliber cartridge is equivalent to 10mm in diameter. As noted, the size of a handgun can vary widely within one caliber, so it is perfectly reasonable to have a smaller handgun crafted in a larger caliber.
No. A smaller caliber will either not fire at all, or will split the cartridge casing if it does fire.
Properly written as .10 caliber (notice the decimal ?) a .10 caliber firearm would fire a VERY tiny bullet- 1/10th of an inch in diameter- less than half the size of a .22 caliber. However, since very few firms have ever made a cartridge that tiny, you MAY be referring to a 10 GAUGE shotgun- which is VERY large- about 3/4ths of an inch in diameter. With shotguns, the smaller the gauge, the bigger the shell.
In the usual sense of caliber, it means the diameter of the bullet. The smallest commercial caliber is the .17 rimfire, but there have been MUCH smaller caliber firearms, down to the 1-2 mm range. That is about .05 to .10 caliber.