OK, I was able to duplicate this on my Shield 9mm. It took both hands to do it, but I could get it up there. I can't imagine a normal shooting situation where this would happen. It took a lot of force to move mine up on the stop. I was able to pry it back down without too much difficulty.

I don't think this is a design flaw. It takes a lot of effort to make it stick like this. I don't know what the OP was doing or what his situation was, but if this happened during normal range shooting, the trigger is defective.

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