Here's an email I had with PSA. It was vague...I don't feel like my question was answered, but here it is if it helps:
Greetings,
What is the difference between the 20" 5.56 Hammer Forged, Chrome-Lined MP Upper
http://palmettostatearmory.com/2522.php which is in stock,
and the "Palmetto State Armory 20'' 5.56 NATO FN Upper" which is
temporarily out of stock?
When will the latter be back in stock?
The differences are very minor, but essentially it is a difference in the
barrel manufacturers. The configuration that is out of stock is waiting on
barrels at this time. We should get them in as early as mid January and
then be able to hopefully be able to have them ready to sell by the
beginning of February.
Please let us know if there is anything else we can help you with.
Thanks for your inquiry,
Customer Service
Palmetto State Armory
Thanks for the info. So the out of stock ones are made by FN and
hammer forged, while the in stock ones are hammer forged but not FN?
Thanks
Not hammer forged are also non FN correct.
Please let us know if there is anything else we can help you with.
Thanks for your inquiry,
Customer Service
Palmetto State Armory