[ILLusion]

This is caused by the crappy tolerances between the slide and the barrel. Over time and use, the barrel eventually chews through the lugs in the slide that are used to engage the chamber and pull it back. Once the lugs are worn down and the slide can no longer reliably grab & pull the barrel back, the slide ends up getting caught on the top of the chamber, which dramatically increases the damage to the slide.

At this point, there are three solutions, but only two of them are reliable:

1. The first solution is to get a replacement slide. If you get a KJW one, this problem may happen again. If you get any other brand of slide, it may not play well with your barrel, AND/OR if you are able to get the slide to cycle the pistol properly, the barrel may again, chew up the lugs in the slide. This is not a positive, but based on the lack of information in this area, and based on the prices of a quality aftermarket slide, it's best not to guess with this one.
   However, as Thenooblord has pointed out, there is a second and third solution.
   
2. The second solution, is a two piece outer barrel system, pre-loaded with a spring - it's a custom modification that I figured out a couple of years ago before any other solutions were on the market. If you dig around enough, you may find some tutorials or pictures online of how such a setup looks. Basically, it is a two-piece barrel system, with a spring attached to the inner barrel and levers it against the chamber. The outer barrel just covers the assembly. The result, is that the natural state state of the outer barrel, is now to pull backwards, rather than rest in a neutral state. By doing so, the barrel & chamber does not rely on the slide's lugs to pull it back anymore, instead, the spring does this for the slide and the end result is a barrel that (on its own power) follows the slide back naturally. The downside to this, is that now the slide's forward lug now bears the force of returning the barrel to battery AND pushing the spring forward at the same time. If this lug is still in perfect shape, then this shouldn't be an issue, but it WILL take more damage and break down faster. It shouldn't be too much worse, since the spring should only be light weight. However, if that lug is destroyed, then your only reliable option is the third solution...
   
3. The third solution is ILLusion Kinetics fixed barrel, which offloads all contact that the slide makes with the barrel/chamber, which increases the slide life to an infinite level. Even a completely internally destroyed slide can function properly with this barrel set. The barrel does not move, it does not tilt or rock. It's stationary. The chamber top is lowered a slight bit, so that the slide just glides over the chamber cover. This type of barrel works with any brand of slide, regardless of its health.