With facination, I just learned about the earliest known, semi-auto rifle issuet to troops, the 1908 Mexican Mondragon rifle in 7 X 57 Mauser.
Find it on the web under "Mondragon rifle" and www.cruffler.com/historic-february01.html
Find it on the web under "Mondragon rifle" and www.cruffler.com/historic-february01.html