[ILLusion]

I've fixed this problem on multiple barrel setups, but it can only be done on barrel setups that allow the chamber to separate from the outer barrel portion.

Essentially, what's done, is a spring is applied to pre-load the chamber against the hop up unit. What happens, is that the outer barrel's natural state is to pull back - the only thing that keeps it forward is the slide when in battery.

Once installed, regardless of which way the pistol is pointed, when the slide racks back, the barrel will automatically pull back and no longer relies on the internal lugs - this greatly increases the durability of the slide in that area, and also saves the nice shiny finish on your chamber (avoids scratching.)

It looks like what safx posted a picture of.

I use an old recoil spring (you only need a couple of winds... 4 or 5 is sufficient) and I widen it a little bit to allow friction-free movement. It's then secured in place with electrical tape. Just need enough winds to allow the outer barrel to still fit over it.

I've also found a solution for one-piece metal barrel setups (like the ones I custom make) that fixes the barrel in place. Same idea as the Tokyo Marui Hi-Capa Xtreme barrel. I can also make these in 5.1 threaded length - these fixed one-piece metal barrels are actually your best solution if you're looking for something threaded to hang something off of. Regardless of the size/weight/length of the attachment, it will not affect performance.