I've got a Bushy M4 upper And I can't see a line where the break and barrel meet . There is just a smooth transition ,But I shined a light in the end of the break and can see threads .Also I can't find a spot for it to be pinned But there are two flat spots on the left and right side of the break . I'm sure if I grind on one or the other I should be able to find something right ? Also where can I find a FSB with a Bayo lug ? This is all I need to complete My noban I already got a RRA 6 pos stock ! Thanks Jeremy

anyone?

The flat spots on your FS are for a wrench.  Do NOT grind these down, you will not be able to get it off.  Just forward of these there should be a spot that hopefully is discolored.  This is where the pin is welded.  That is where you need to gind it down a little to free the pin and then unscrew the FS.  If you do a search you should be able to located several threads on this topic.  Some members have posted another way to remove a FS which involves cutting into the FS from the bore toward the upper and then separating the halves.  I would just look for the spot that is reblued and go from ther.

Sarge

As for the new FSB, probably Bushmaster would be the best choice to make replacement the easiest.