12 Guage is the least expensive ammo. It is the most commonly used. For most common loads 20 guage can easily be found at the same prices.

NO!!!!!!!!!!!!!!!!! DO NOT TRY THIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Full sized .30 caliber cartridge, developed in 1906.

None. A primer does not contain propellant powder- it contains an explosive that ignites the powder. If you mean how much propellant powder is in a 9mm cartridge, that will depend on which 9mm cartridge (there are nearly a dozen different 9mms) which weight bullet, and which powder. My basic reload data table for 9mm Parabellum (9mm Luger) is 3 pages of data with different powders, bullets, etc. A basic load is 4.5 grains of Bullseye powder with a 115 grain bullet.

Yes

It is possible, but extremely rare, to survive a gunshot wound to the head.

About 3.5 ounces.

2 in x .050 in

There isn't a difference. Mainly because .38 Special IS the standard .38.

The "Special" in .38 Special is simply a marketing word. The term was used to distinguish it from the earlier .38 Colt, which is now obsolete.

In modern terminology a ".38" is an abbreviation of .38 Special.

Now, just in case you did not ask the question you meant to...

Another common question is the difference between .38 Special and .357 Magnum. The .357 Magnum was designed as an "enhanced" version of the .38 Special allowing more powder to be stored in the casing and thus deliver more power to propel the bullet. The .357 Magnum is much more powerful and has much higher gas pressures, and thus it is not safe to shoot a .357 Magnum out of a gun designed for .38 Special. Fortunately most modern .38 Special revolvers are designed so that the longer .357 Magnum will not fit in the cylinder. The reverse however is permissible as .38 Special can be fired in a gun intended for .357 Magnum because the magnum-gun is built much more sturdily than required to shoot a .38 Special.