Try tapping on the back of the FS to move it forward. You've probably moved the castlenut as far as it wil go forward & if the splines on the FS & barrel are mated tight you won't budge the castlenut until you move the FS forward some more.
HTH
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The only hope you have is to accept the fact that you are already dead. And the sooner you accept that, the sooner you will be able to function as a soldier is supposed to function, without mercy, without compassion, without remorse.