Exactly what occurred with one of my brand new Glock 30's a few months ago...

1. Your Shield is defective and it is firing out of battery (fully locked up). It is UNSAFE to fire because a cartridge web blowout could blind you or seriously injure you. As was so correctly pointed out in a previous post, your firing pin is striking the primer off-center because your barrel is slightly lower than it should be when properly and fully locked up. This is a MAJOR defect. Although most guns can be manually forced to fire like yours, this should never happen in a properly functioning pistol.

2. This MAJOR defect can be caused by conditions like an out-of-spec or improper barrel-to-slide fit; an out-of-spec or weak recoil spring assembly; defective locking block; excess binding of the barrel, slide, or frame; and several other SERIOUS flaws.

3. It IS NOT caused by ammunition. When the recoil-operated Shield unlocks, it must be driven back into full battery solely by the action of the recoil spring assembly. (Imagine a recoil spring assembly that is not strong enough or long enough to force the slide fully forward - same result as yours).

4. Although, under some circumstances, your Shield's failure to lock up may minimize or seem to disappear after firing a number of times, it will never reliably lock up as it was designed to do.

This Shield needs to be properly repaired or replaced by Smith & Wesson.