Front sight question

[Slater]

I was watching one of Chris Bartocci's videos on the Bushmaster M4A2 Patrolman's Carbine (apparently he liked it so much he bought the evaluation gun). This version has a fixed A2 carry handle but he noted that it had an "F' marked front sight base. A couple months ago I was looking over a Bushmaster M4A3 in a local shop. This had the removable carry handle and also had an "F" marked FSB.

My understanding is that the "F" marked FSB is only intended for flattop carbines with the removable carry handle. For a fixed A2 version, how would this affect the sighting/accuracy (if at all)?

[Renegade04]

It does not affect it much at all. I have used F marked FSBs with A1 and A2 uppers with no zeroing issues at all. You may have to run the front sight post down a bit to compensate for the taller FSB. That is about it.

[utahjeepr]

The difference between the two is 0.04 inches (1/25th of an inch, just barely over 1mm)

[Hammer_Man]

I used a Windham barrel with an F marked sight base for my A2 build, and it zeroed just fine.