I put one in when I was young and stupid... and trusted my local gunshop that it was actually half decent. It was proper ******e in my Vulcan to be honest. Then I put a gas ram in, and now it shoots quite nicely.
Just for the hell of it I tried to get the Ox spring working nicely, I cut several coils off it and gave the ends some serious polishing. It is only 'OK' - Id much rather have a decent spring or even just a plain old replacement one from Chambers than get an Ox spring again. Bloody 'orrible things.