Just did one on Saturday, I was installing a free floating forearm. My friend didn't trust one that came with the unit, he didn't trust the two allen screws . I had to Grind down the Stock front sight, between sticking it in the already bolted down vise, clamping it with my vise barrel attachment, opening the cabinet door, plugging in my Dewalt grinder, A quick measure, a easy cut, and a smooth finish, Probably took all of two maybe two and a half minutes. The great thing about this was no need to knock out the gas tube pin, nor remove the flash hider. I personally would have changed out the gas block in this particular situation, but for the rugged use my friend has in mind, a cut down stock front sight with two pins was his choice.