So I'm trying to get the gas block off my new pistol upper. I'm not a gunsmith or certified armorer, but I do have enough mechanical experience to know what's fixing to happen if I force such a tiny allen wrench. I've put enough pressure on it to make me uncomfortable, but the screw hasn't budged. I've heated the gas block a little with a small butane torch and nothing. Any advice? I'm using a 3/32" allen wrench, which seems to have a little slop, while 2mm is too small and 2.5mm is too big. Yeah, metric or standard?