Jun 5, "United States Beer Cans, Vol I": by the Brewery Collectibles Club of America, discusses methods of dating flat top and cone top beer cans.
However, it is overwhelmingly likely that the appearance of the tax statement places the can between and and the lack of such a statement places the can after March 30, As time passed and manufacturing processes improved, the dating and weight of cans decreased.
Cans were made mostly of steel from through about With many exceptions, steel cans generally date between and and aluminum cans date after Early mostly s cans have extensive dating on a back side extolling the virtues of cans as a vessel for beer. Consumers also had to be educated on how to open the early flat tops so earlier mostly from through about flat top cans had instructions on how to open the cans on the back.
The first such "instructionals" often featured a picture of a churchkey opener that vertically spanned from the top to the bottom of the can.