I've experienced this sort of thing with every G27 I've tried (four or five and counting, including a Gen4). What I've found is that, for whatever reason, the G27 is highly sensitive to "limp wristing" and if you don't have a perfect grip on the pistol, the slide will not go fully into battery. Being slightly out of battery, the firing pin will move when the trigger is pulled and strike the primer but not hard enough to ignite it. Since I can't guarantee a perfect grip in a backup pistol, I don't carry a G27. In fact, I don't own one anymore. If you are using G23 or G22 magazines, the malfunction issues will be exacerbated, from what I've seen on the range. From what I've seen with dozens of examples of G27s being fired by other shooters, it seems to be one of the least reliable Glock models.
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