What was the most widely used firearm in World War 2?

Answer 1

One of the most widely used weapons was the Lee-Enfield bolt action rifle, which was issued to all British and Commonwealth soldiers. In total approximately 17 million units (including all variants of the rifle) were constructed, however it is unclear from the source exactly how many were used during World War 2.

Another very widely used weapon was the Mosin-Nagent which was the primary weapon of Soviet troops. By the end of World War 2 approximately 17.4 million units of the M91/30 version of the rifle had been produced.

For US forces, the standard rifle for the infantry was the M1 Garand, with approximately 4 million units being produced during World War 2.