It would depend on caliber, for a .44 caliber you would use a .441 to .445 ball, for 36 cal use a .362 - .365 ball or conical bullet, You want to have your ball slightly larger than the chamber size so when seated you shave a thin ring as the ball is rammed into the cylinder chamber thus sealing the powder charge from moisture and cross fire and giving the best performance with your load.
No. The ACP has no rim so it cannot be used in a revolver that is not designed to hold the cartridges in a clip. It is also slightly smaller in diameter than the LC (shorter, too, but that shouldn't matter in a revolver). But mostly, if you could get around those differences, the ACP uses smokeless powder and the LC was designed for black powder.
Yes.
Back when the round was powered by black powder, the "20" meant the amount in grains of the powder charge.
Yes
It is the round with which the revolver was "proof fired" at the factory to test its functionality.
A revolver with a 6 round capacity.
It is for cloth patches that were used to make the round lead ball fit titer in the barrel.thus creating a titer seal over the powder and gripping the rifeling.
NO
Nothing, really, but the name of the cartridge. When Winchester introduced the Model 94 in 1894 in the brand new smokeless powder round .30 Winchester caliber, most of the other ammunition on the market was black powder and had names such as 25-20, 44-40, 45-70, etc. These names stood for the caliber (diameter of the bullet) and how many grains of black powder were in the load. The .30 Winchester didn't follow that convention an dpeople didn't know what to expect, so it was not well accepted in the market and sold poorly. In a marketing move, Winchester changed the name to 30-30 (still, of course, a smokeless powder round with identical components as the .30 Winchester) and the guns and ammunition sold quite well.
You take the radius (or diameter). If radius you times it by two (since it is half of the Diameter) then times the answer by 3.14. If diameter, times the diameter by 3.14. then round the decimals.
Pistol, revolver, rifle, gun. If you mean the device which holds rounds of ammunition, that would be a magazine. If you mean the parts of a firearms "round" you have 4 parts. Primer,casing,powder,bullet.
The 9mm round in loaded with a bullet diameter of .356"in.