Unknown Upper

[A324]

Need assistance in trying to determine the maker of this upper. Only visible markings are "FK" near the rear sight and "5.56" on the barrel.

[black_hawk06]

re: upper

most likely this is made by LMT

[PIRATE14]

most likely this is made by LMT

LMAO........

[bwiese]

LMAO........

Yeah, not 100% sure but I think this is a bottom-feeder upper too.

[6172crew]

I think FK was a bushmaster marking.

Found this on ar15.com
CAF Colt / Alcoa Forge (See above for photo)
CH Colt / Harvey Aluminum (1st Colt Forgings)
CM Colt / Martin Marietta (See above for photos)
DK Diemaco / Kaiser
FK, FS, BK, DK, EK, FK, AF, CW, AA, FS Bushmaster
LK FN / Kaiser
LM LAR / Martin Marietta (Army Spares Contract)
Splintered A Olympic Arms

[DRM6000]

it may be a bushmaster upper receiver as noted in the post above mine, but i don't know.

the barrel though, afaik isn't a bushmaster. the marking on the barrel of one should start with: B MP 5.56 (i can't remember the rest.)

[Biff...]

If its a Bushmaster upper the barrel should be stamped like this

[mltrading]

most likely this is made by LMT

Does LMT make 20" upper? AFAIK, the answer is no.

[A324]

Thanks for the replies, the original owner had numerous registered AR's including many AR parts and had expired (assumed room temperature) in February and I've been trying to identify and find new homes for them.

[A324]

Correct, the same markings are found on my BM barrel but I also seem to recall reading somwhere that a particular barrel maker leaves only "5.56" stamped on their barrels simular to the one in my photo.

If its a Bushmaster upper the barrel should be stamped like this