50 and up
Your question is far too broad to answer. Large caliber rifles prior to 1918 included everything from the Civil War era, buffalo guns, and even the incredibly large British rifles for African big game. There was even a WW I anti-tank rifle- made prior to 1918.
Podhale Rifles was created in 1918.
Tanks, Rifles, French Lebel
In 1918
1918
1918
The Tulsa four. From 1918 to 1921
Manufactured late 1918
1918
made by colt 1918
The year should be stamped on the top of the chamber. If you cannot see this, you can get a better idea by knowing which model it is specifically (see related link at the bottom). In the case of the M1891 rifles manufactured by New England Westinghouse, they're all marked 1915, even though they were actually manufactured from 1915 to 1918. In the case of the Finnish rifles, the year you see stamped on the outside is simply the year the rifle was refurbished into whatever model (M24, M37, M38, M39, etc), and you would have to check the tang date to find out when the receiver was actually manufactured, and by whom.
if the military model, about 1918