so each type has a different diameter for gas to flow into the valve 3.5, 4, 4.5 and 5mm and each also has an adjustment screw to allow more or less gas into the cylinder. The question is, and there is nothing on the G&P website, what values does each 1 cover?
Anyone seen a chart with say Model A with 134A at 20C ranges from 310 - 340 FPS?
The only other way to find out is to buy 1 and see what it provides and then possibly go buy another size based on the results from testing the first one and hoping you got it right.