There were many types of guns used in World War 2. Their was the Bolt-action rifles, Sniper Rifles, Semi-Automatic Rifles, Sub Machine Guns, Assault Rifles, Pistols, and Light Machine Guns. I will tell you about all of these guns.
When World War 2 begun, most soldiers were equipped with Bolt-action rifles and were replaced during the war by newer weapons. Bolt-action rifle are sturdy and reliable. World War One had demonstrated to all armies the need to place a greater volume of fire. Bolt-action rifles were untested before given to soldiers. Sniper Rifles have long range and high accuracy. These are bolt-action rifles which are adapted with magnifying telescopic sights, and often also with additional enhancements such as bipods, cushions, and higher standard production, all in order to maximize the sniper's ability to deliver the few selective shots. Advances in technology, specifically that of telescopic sights and more accurate manufacturing, allowed armies to equip specially trained soldiers with rifles that enable them to deliver precise shots over greater distances than regular infantry weapons. The rifle itself could be based on a standard.
Semi-Automatic Rifles provided the soldier with a significantly faster rate of fire. These quickly became the basic personal weapons of World War 2 soldiers. A total of over 6.5 million M1 carbines of various models were manufactured, making it the most produced small arm for the American military during World War II.
Sub Machine Guns were an invention from the end of World War 1, these are the small machine guns, capable of a rapid rate of automatic fire and they were also mechanically very simple and reliable. They were very cheap and easy to produce. Their main disadvantage is their lower range and accuracy.
Assault Rifles were developed and used by the German army. Assault rifles such as the American M-16 and the Russian AK-47 are the basic weapon of the modern soldier.