FN M4A1 upper.

[ABNAK]

First of all, it's a 16" barrel and not 14.5" like a true SOCOM would be (for gov't production anyway). It also is lacking the M203 flat cuts behind the FSB.

[Jmedic_]

Junk RR upper with a button rifled FN barrel. It never has been and never will be a FN M4 upper!!! Where is the value?

Totally agree. I’m not sure why I thought the upper was “F” marked.