A misfire is when a person pulls trigger on loaded firearm and it does not fire. Shortening a handgun barrel a 16th of an inch will not cause a misfire or malfunction.
They say that the 3-D printed plastic gun can get by metal detectors and xray machines. While the printed plastic gun contains no metal, it requires a metal firing pin and the ammo will also be metal, so it's not truly accurate to say that the printed gun can get around security measures.