Here's a pic of some adjustments screws that I plan to try out for an adjustable gas block. The one on the left is the adjustment valve from a standard automitive style spray paint gun. I had it put up in my toolbox, and didn't realize exactly how large the diameter was. It would work great on a home made large block style gas block, but not to add to a factory gas block. It's just too big to use, approximately .500" OD. The one on the right came from some tool or another and I scavenged it before the item went into the trash. I think it's 1/4"-28 threads, so it's small enough to use on a standard AK74 style 90 degree gas block. I was thinking of drilling and tapping directly above the gas hole where the needle valve can basically just be screwed down deeper into the hole to block the gas, and there is even a jamb nut to lock it in place. Just a thought.