I had a similar thing happen with my 45APC pistol a few years ago now. I ended up installing it in my vice and useing a wrench with the open end to go over the slide end and hit it with a hammer. It was a swollen cartridge inside that had jammed mine up. I have rubber grips for my vice which will grab the gun very tightly and stay in place when locked down very tightly. This did not take very long to make it work at all. A couple of good blows from the hammer and it popped open enough to get the caseing out. I gave it a good cleaning and lube job and its back in the lineup ever since.