Q: What style of hop-up does the outer barrel work with?
A: Our outer barrel has been designed to fit the standard hop-up units shown in the photos attached below (click on the images to enlarge). It works for single piece and two piece hop-up units. These units are common in APS, JG, Black Ops, King Arms, and many other airsoft electronic guns (AEG). It may require slight modification for use on other brands.
Q: Does the outer barrel work with rotary style hop-up unit?
A: We have not tried the outer barrel with a rotary style hop-up unit. But one of our customers has mentioned that his G&G rotary style hop-up unit does not fit. Our outer barrels are designed to replicate standard M4 outer barrels. So if a rotary style hop-up unit fits a standard M4 outer barrel, then it should work with our outer barrel. At this time, we do not know the issue that caused the reported failure.