While most of Europe was already noting the rising tensions, they stayed with their bolt action rifle leaving the US to be the only country to enter the war with the vast majority of its troops sporting an autoloader, though some countries attempted to get autoloading rifles into mass production in the middle of the war.
In a follow-up, did the various European nations seek out semiauto designs for widespread issue without success, or did they feel it was unnecessary at the time?
The US wasn't the only army to develop semi-auto rifles. The Germans developed the Gewehr series of rifles, based originally on a Czech design. ZH-29 (Czech) AutomatgevÃĪr m/42 (Sweden), AVS-36, SVT-40 (Soviet Union), Fucile Armaguerra Mod. 39 (Italy), Fucile Armaguerra Mod. 39 (France), and Kbsp wz. 1938M (Poland). In some cases these were put into service later in the war (Italy).
Most countries considered Semi-auto weapons to be superior to bolt action rifles, but only a few countries had the resources to build, buy, and equip the more expensive weapon for every soldier. These rifles tended to end up in the hands of more elite formations, such as the German paratroopers.
Basically, most countries had a design, the French as early as 1918. But cost, need during the interwar years, and then cost again during the war when resources were spread thin prevented the rapid spread outside of the US, who uniquely could afford to buy them en mass.