I intend on mounting a 3-9x38 scope on a flat top upper. If I order a standard BCM upper with the FSB will the front sight obstruct the scope requiring me to mount the scope higher than ergonimically optimal ( I want to be able to maintain a cheekweld.)

It will basically be a scope only gun, unfortunately I missed out on the S&W OR deal and can't find another quality rifle without a FSB, and don't know if it is even an issue.