I have seen this with many other triggers besides Jewel. When CZ first brought their center fire carbine, it had a set trigger. It was bad about the same thing, and experimentation showed that there was no way to get out of it. If you set the trigger with a chambered round and set the safety, there no course but to find a safe place to point it and hold on while you flipped the safety off. If I remember correctly, you could not cycle the bolt on safe. I suspect this is the reason the trigger wasn't sold for long. They did the same thing in a way with their factory replacement fot their rimfire rifles. Called a Hummingbird or something similar. Great trigger, but very easy to adjust past the point of reliability.
With the Jewel, it is sometimes related to the action and trigger needing to be timed as to engagement. It is more common with commercial and modified commercial actions than with high end clone actions.
