I have a LH Stag AR with the standard front sight that is pinned. I have a scope on it and want to replace the front sight with a gas block. How hard is this if I do it myself? The gun shops I have asked will charge around $150.00 to $175.00 to do this. If I cannot do this myself I will save my coins and buy a new upper with the gas block Let me know Thanks Wanna kill these ads? We can help!