So I have a few Krebs safety selectors some I've installed, others I haven't. Others have just been waiting for use. I installed a new one on a sgl31 that i just put a new tapco trigger group in. I flipped up the selector and pulled the trigger to make sure it was locked. Then I hear click. The hammer dropped. The trigger doesn't pull all the way, when you release the trigger, the hammer will release. I put the same safety selector and trigger in a different rifle to see what was what or if I could recreate it. I cannot. My guess is its something specifically with that sgl31. Is it possible the trigger holes being off could cause this? They don't look off. I've just never seen anything like this.