I believe they are date stamped like the rifles on the barrel, see related links for information and look-up table.
Manufactured 1919
Your 1911A1 pistol was made in 1944.
YES REMINGTON FIREBALL , OLD PRODUCTION. Also, a number of companies make AR pistols in .223.
You will have to contact Remington to find out.
Look at the date code or call Remington, see related links
You will have to call S&W to find out.
Call Colt
You will have to call Colt to find out.
check in with ANTIQUEGUNLIST.COM and ask them who you can send pictures to in order to identify your pistol... also furnish details where pistol was found.
It's date stamped on the barrel. Check the Remington Society of America's manufactured date link for details.
You will have to call them to find out.
Old gun catalogs would be a place to start