There were numerous rifles in WWI, due to the numerous nations involved, but a few typical rifles were the Gewehr 98 of the German army, the Lee-Enfield rifle of the British Army and the M1903 Springfield rifle of the US Army. The Gewehr 98 weighed around 9lbs or 4.08kg, the Lee-Enfield weighed 8.8lbs or 4kg and the Springfield weighed 8.67lbs or 3.9kg.
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The rifle was the main gun of the Infantry man so every major battle in WW 1 the rifle was used.
M1917
The SMLE. Short Magazine Lee Enfield rifle. Picture above.
During World War 1 some of the weapons they used were Chlorine and mustard gases, pistols, artillery, mounted machine guns, pistols, bayonets, grenades, zepplins, tanks, u-boats, tanks and bi-planes they did not have weapons like the bazooka or the missile launcher until after world war 1.