I'm just curious how the OP can know so much about AR15's and gas blocks, but know nothing about rifle optics.
You can also CUT the front sight base down. Of course, there is no going back once you do it, but if you are leaving the gun as is, this is an option I've seen done by a number of people. It's a solid, cheap fix. Just cut, smooth and refinish. You wouldn't be able to mount anything to the base like you would a railed gas block, but that might not be an issue. You would also get to keep the bayonet lug, if you have one.
You can also avoid removing the flash supressor or other muzzle device. No big deal if it's threaded on, just a new crush washer, but if it's pinned on, this saves you a big PITA.
