Lol, okay. What exactly causes BTF?
That's the million dollar question. There have been tons of theory's on it, most believe it's the extractor or the ejector. I have read a lot about the apex extractor and that it will fix it, if you have the issue. Some say the older ones do it, some say the new ones do it. I had one 19 that did it more than the others. It was not that often and it did not bother me. My current 19 gen4 has never had an issue of any kind. It does not effect the function of the gun.