Re: AR10 Barrel Nut
I have an AR-10T and I have a standard AR10 that built from the ground up. When it comes to the thread on the AR10 receiver, they're both the same. When it comes to the wrench that is needed for an Armalite AR-10 Freefloat tube, you need to use a different wrench.
The standard Armalite barrel nut is designed to use a delta ring assembly so that you can attach standard AR15 A2 handguards to it. Because of this, the notches that are in the barrel nut are used only for indexing with the barrel nut wrench and lining up the handguards. Normally on an AR15 they also help support the gas tube. Because of this the standard AR10 barrel nut uses a standard AR15 barrel nut wrench.
Since the freefloat has a barrel nut with a lock ring that retains the freefloat, there are holes in the barrel nut for the gas tube to pass through. Since the entire action is bigger, those holes are offset at a greater distance from the bore axis. These holes are what the AR10 freefloat barrel nut wrench interfaces with. Thus it's a specific barrel wrench for the Armalite AR10 Freefloat.
From the Troy rails I've seen, they us the pre-existing "standard A2" type barrel nut and you just remove the delta ring assembly. So I'm guessing that a standard AR15 barrel nut wrench would be all that's needed.
Daniel defense Lite rails would use a nut that works with a spanner that is very similar to (if not the same) as a castle nut spanner.
Superior Weapons System E1 rails use a totally different type of nut and come with their own barrel nut wrench. (I have two of these, they are nice.)
I'm not 100% but I think that Larue would use the AR-10 free float specific barrel nut wrench since it's one of the only freefloat designs for the AR-10 that uses a locking ring.
*Edit*
I should also add that even though certain rails might use the standard A2 "style" barrel nut, they are in now way the same as and AR15 free float. Due to the size of the action the top rail is quite a bit higher than normal. I bet there a lot of other subtle differences besides that.