almost sounds like the hole in the huma may have clipped a few pellets slowing it down , did you try opening up the Hole ? I have used Huma regs and they make a great product . could also be the Donny had a larger hole in it and something like adapter shroud or barrel isnt square and it clipped , Huma is a great company and would sort it out if you called them . I had similar issue with a moderator I wont say which brand , but it did almost same and it was not moderator it was a shroud which was off by a hair and it clipped now and then ,
The repair was open the hole a whisker , it may have been fine in 20 other guns but that one had a problem , but to say you would give it to your completer in a shooting even , come on the company is a quality company and they do stand behind things if there is ever a problem , but you know it mite have been the gun or shroud not perfectly square , you cant trash them from 1 simple YouTube video
LOU