Ask and I appear....
In the very first batch of mags, the front and back of the regulator were made on screw machines. The air flow hole from the on/off on the front half was always at the top where it is now. The back half of the reg had a hole drilled randomly 360 degrees in a circle that was machined into the reg body so the air would flow around and get to the hole.
John Sosta figured out that if you happened to get a reg where the two holes were 180 degrees apart, the air flow wou...