It also helps that up into the 1980’s and 90’s, small arms that weren’t considered modern enough to issue to frontline military forces were often offloaded to the various militias in China (ie able bodied civilians that were given a crash course on how to use a weapon in the off chance China was invaded during the Cold War).

These groups didn’t start getting disbanded and disarmed until the 80’s, so you still had villages/towns with the equivalent of WW2 era and early Cold War weapons and ammunition on hand for the hypothetical invasion of China.

One of the ways they managed to disarm them was to take all those weapons and ship them off to the US as commercial arms sales during the 80’s and 90’s; the government made money off US gun owners for buying up old milsurp guns, and they managed to implement gun control by taking those arms out of the hands of the militias for the sake of “economic prosperity and public safety”.