As to the Shield, it's very visible. There could be a piece of paper caught in it, etc. Does the user tap the bottom of the mag, to make sure it's seated, etc. As far as my thoughts go, this doesn't apply directly to the OP. Just a generalized reaction, to comments in this thread, as well as other threads of this type. With the Shield, it's really a easy product to shine a flashlight in the mag well. A problem should be very obvious. If something is broke, it's broke. If anything is catching the mechanism, then clean it out.