I do not necessarily trust "fact checking" sites like this but:

Strict German gun regulation was in place before Hitler rose to power and he later oversaw gun laws that loosened many firearm restrictions.

According to a 2004 analysis by Bernard Harcourt, a professor at Columbia University, after the Germany’s defeat in World War I, the Weimar Republic, the government that preceded Hitler’s, passed very stringent gun laws that essentially banned all gun ownership in an attempt to both stabilize the country and to comply with the Treaty of Versailles of 1919.

By the time the Nazi Party came around in the early 1930s, a 1928 gun registration law had replaced the total ban and, instead, created a permit system to own and sell firearms and ammunition.

Dresden Technical University in Germany, told PolitiFact in 2015 that the order was followed "quite rarely, so that largely, only newly bought weapons became registered. At that time, most men, and many women, still owned the weapons they acquired before or during the first World War."

In 1938, the Nazis adopted the German Weapons Act, which "deregulated the acquisition and transfer of rifles and shotguns as well as ammunition,"