The only way to get a bayonet lug on my AR10A4 is to get a fixed front sight base.  I know I don't really need the bayo lug, but it just pisses off the Kerrys and Fineswines of the world when we do that.

Here is the only picture I have of this rifle (member cat_aclysm shooting it, I hope you don't mind cat) and just want to know if y'all think I should forego the lug and keep the flat top front sight.  I already tried that scope pictured on an older A4 carbine with a fixed front sight just to see if it is a distraction and you don't even see it.  Could it cause some distortion or other problem by having the sight there?  Either way, I am definately getting the FS on it and get rid of the brake.

I've got an A2 FSB on my CAR15 flattop, and using a 6x scope I can't see it, and my scope sits lower than yours. When I had a 3-9x scope I could see a phantom when on 3x. As long as you shoot with it on mid to high magnification, you should be fine.

I'm keeping my A4 as clean as possible.  That is, no muzzle brake or FS installed since there several arguments (pro and con) saying that anything in front of the muzzle compromises the accuracy.
Therefore, just in case, I'll leave it just with the FT style crown and the floated barrel.   As a bayo lug is of no use for FT I'll leave it out also.   However, I have plans for a collapsible stock for the lower.