I have a Kel Tec P-11 9mm I took it out yesterday for some range time. Before I fired it I was showing my brother how it breaks down for cleaning. After I pulled the slide pin and released the slide it only moved part way and got stuck. I had to push it off the rest of the way. Got it put back together and function check seemed normal so I went ahead and fired it. Everything worked well, ran 50 rds through it and called it a day. Got home and went to clean it, had the same issue so I scrubbed and oiled every part, put it back together, function checked then tried to break it down again and it's still sticking. What am I missing here?