What is Autococker barrel threads?

Answer 1

As more companies started making Paintball markers, there started to be MANY companies that made aftermarket barrels, however it was cheaper for them if there was a universal fitting for the barrels instead of dozens. Many of the companies decided that WGP's Autococker was a popular marker with a strong but easy to make barrel thread, and adopted it as the thread most barrels would be made in.

To this day, even with WGP's decline, it is still the standard thread for most markers.