I have an Osprey kit I'm going to be using.
I ordered the Primary Arms Seekins Precision 15" tube.
I have read that the Osprey op rod needs to be changed out for a modified part in order to interface with a free float barrel nut.
I have also read that the new Seekins barrel nuts work just fine.
I got the tube in today and am trying to figure out if this barrel nut will work with my op rod, or if I need to trade it out with Osprey.

Assemble the system with the gas block in place. If the end of the piston rod contacts the barrel nut at the same time that the piston completes it's travel (look for the thicker part of the piston to be flush with the opening of the port) then you are good to go.

-Jim

it should function just fine.