Took my new SW1911PD (5" w/tac rail, TLR-2 attached) to the range for it's first time through the paces and it fired the first two mags without a hitch. Ammo was Federal 230gr FMJ 45ACP with brass casings. Third mag went in, two shots went off without a hitch. Third shot went off, it racked the slide and chambered a new round but it did not lock the hammer back (the hammer rode the slide back forward). I manually cocked it and it fired but did the same thing again. I clicked the safety up and down to make sure it wasn't the cause (because the safety on the gun doesnt have very good feel as far as when it's on, off or somewhere in between), then manually cocked it again. This time it fired twice before doing it again. This went on for the remainder of the 50 rounds I went through before hanging it up and going back to the other guns I was testing for work. I'm already sending it back to S&W because it's only a week and a half old, but any thoughts from the experts on what it might be? When I rack the side and run snap caps through, it's not doing it, it's only doing it when I was firing live rounds. Thanks!