The shell may be loaded with a slug or shot (size 0000 all the way up to #12 or dust shot), with the shot being made of either lead, steel, copper, bismuth or tungsten etc.
On some headstamps (Especially Brass) there may also be an A or a B after the gauge.
This is mainly used to represents the shell type or lot by some manufactures, for others it indicates the ability of the shell to be reloaded.For other manufactures, the A or B has represented the powder (Smokeless or not).Dates after company name indicates known dates of the company being in business.An * after the shell represents the shell is generally a brass shotshell, but the headstamp may be found on others)(1898 to 1932.Solid brass shell casings have come and gone, and so have the cardboard shells that were loaded with such bird shot charges such as “chilled” lead shot.
Propellants have gone from black powder to smokeless, which helped hunters keep an eye on targeted game after the shot rather than through a smoke screen.
The color of the plastic or paper hull as well as the case size and the size of the brass rim must also be taken in to consideration for identification purposes, as well as the color, size and type of primer used.
Primer size, color, type and size have changed over the years and can sometimes give an idea to the age of a shell.
Note: Exact Shotgun Cartridge Identification requires the identification of both the headstamp, primer and the shell case.
Many companies, such as Winchester may only place a "Winchester" headstamp on the cartridge base for various models of shot shells which are very different from each other.
Unfortunately to Cartridge collectors, just the heads of these shells are absolutely value less.