Alright guys, I know it's been a while since I've been around, haven't started a thread in probably a year, but I have a problem that I just can't seem to solve. I'm working on What?'s C9, last time I worked on it I installed a new mag catch and spring, because the mag would pop out when he would fire it, I thought everything was good until he went out to shoot it and a new problem occurred, with a fully loaded mag it won't fully chamber the first round, it stops about 1/2" short, hard stuck, takes quite a bit to force it home, you can't just smack it, but once you drop the mag the slide moves freely. So, I know you're thinking exactly what I thought, I put the original mag catch back in, thinking that maybe the new one was out of spec and causing the mag to seat higher and create an interference... Nope, it still does it. I've inspected the gun over and over, de-burred, polished and lubed, still no luck. Now, I know better than to do this, and I always used to preach about this when I was on here 24/7, that you should never hand cycle live ammunition in a gun that uses the firing pin as the ejector, but I've cycled numerous mags full of live rounds trying to understand what is happening. Here's what I've learned: 8rnds in mag, slide opened or closed upon mag insertion, will not fully chamber, slide hard stuck, have to drop mag, once the 1st round has chambered, re-insert mag, try to hand cycle it (quickly of course) and it fails the eject and the round actually gets forced into the left side of the slide. 7rnds in mag, slide opened or closed, usually will chamber with a violent power stroke, a lighter but still strong manipulation of the slide will leave it hung up in the same spot, but you can smack the back of the slide and it will go forward, on rare occasions it still gets hard stuck and won't move without dropping the mag, ejects weakly. 6rnds or less, flawless. I don't think it's as much of a clearance issue as it is a tension issue. It's odd that it never had this issue before, and he says it does it with any of the mags he has tried. What could have possibly changed inside the gun that would bring this on?