Those washers are what I was referring to as springs. The assembly acts like a pressure relief, but usually clogged quick and then it was pretty much just like an open plug. I had to send my older gun in for a broken bolt carrier, so I put the original barrel assembly and this style gas plug back in it. They sent it back to me with an open plug.
The new PCC model has a heavier (red) extractor spring that should treat you right for at least 5k rounds.