Here's the deal. I have a standard A2 FSB that I want to remove, and replace with a low profile gas block/FSB with a rail on it. I understand that the factory FSB is custom fit / indexed to the barrel with two pins.
Are there any railed FSB/Gas Block combos on the market out there which make use of set screws and can be installed without custom fitting or removing metal, and which are compatible with flip-up front sights and will reliably hold a zero?