[Ming_the_Merciless]

Thanks for the heads up, that's why airsoft gunsmithing can be a real PITA, part tolerances vary, even if it's the same manufacturer/batch there might be great variance, quality assurance leaves a lot to be desired, but then again they're just toys - not like people's lives are on the line. But I'll take working on a real gun over an airsoft gun any day. As a suggestion I've used some teflon tape a number of times, same tape you use to seal your PVC joints/pipes with, but in this case to sort of shim, to eliminate a slight play between inner and outer barrels, not sure if it will work for the hop up chamber, but doesn't hurt to try.