I bought a used Sig P6 a few weeks ago that came with one mag. Midway only had Promags in stock so I ordered 6. When I insert the Promags and push it up the gun, it feels like it catches but slides out as soon as I shoot. The factory mag works perfect and the Promags will feed if I put my hand under the mag and hold it up there. Any suggestions for fixing this besides sending the mags back?