I just bought a new S&W M&P9c, took it to the range after cleaning the factory oil out of it. Trigger is nice, shoots great, feels great. One problem. After loading one of the mags(10 round) after about the fifth or sixth time(using reliable reloads the whole time), i shot four rounds and the slide stayed back partially. Removed the mag and the jam and found the remaining ammo was rattling around in the mag due to three round being jammed together in the mag. Any known issues and/or fixes for this? I got rid of a Ruger SR9c after 300 rounds because of this same issue with their 10 round mags but i like this firearm better and i want to keep it if this issue can be resolved. Thanks