@Epoxy7: where is this load data that the US gov't had worked up? I am curious and want to take a look. Reloading for the 102 is a mod, so it fits with the intention of this thread.
Look up M118LR (specifically the older pre M14/FN SCAR reloads). The 168 version is M852. Long story short, the 168, 175 Federal Gold are based on this. But... they are downloaded a bit due to having to work in all the rifles in very hot conditions. Which isn't as big a factor for the Bolt and SR 25 rifles as it was for the M14 (breaking operating rods in very high heat).
The powders traditionally used are: IMR 4064 , and RL15. RL15 was dropped a ways back due to temp sensitivity. 4064 is the current, however many including myself use varget. With these three powders the work is already done for you.
The go to rounds: 168 SMK, 43.4 varget, 175 SMK 43.4 varget. 2.8 OAL. Now... a lot of guys use 44 grains of varget. With the 1:10 twist 18.5" barrel, I'm guessing 44 will be the ticket, but will be using the base of 43 (Federal Gold clone), 43.4 and 44. As always do so at your own risk, load up from lower etc etc. Also 168 and 175 Amax bullets are worth a try.
You're looking for that 2600 (175 smk) to 2650 (168 smk) type of range in FPS. Keeping in mind that the Federal Gold round is designed to hit those with a 24" barrel. You lose roughly 100 fps or so with the shorter barrel. A bit of tweaking to make up for the loss of FPS and you should be good to go.
For match off the shelf ammo: 167 Lapua, 168 Federal Gold and 175 Federal Gold. Often if a rifle really likes 168 it won't shoot the 175 as well and vice versa. I will likely try a 150 grain match round as well just to see, as the 1:10 twist should shoot those and lower.
I'm hoping one of those will work well, and am guessing the slightly faster 167 Lapua will be the ticket. Also hoping that the 18.5 barrel gets enough velocity to put the 168 and 175 Federal Gold into the barrel accuracy node. Unfortunately it's not a given. Hence the above reloads.
If it doesn't shoot the above, then it gets a barrel change. No point wasting any more time on it.
I'm Pretty sure that the 102 is an AR10 barrel nut. Am I wrong?
That has been confirmed (for mounting Armalite handguards, but please see below). But people have reported that NEA has also confirmed that the Barrel/Bolt is DPMS systems based. I don't know if this is correct or not at this point. However it very well could be. People have interchanged DPMS/Armalite AR10 Bots/barrels before. The two systems, dimensions are very close. They are only slightly off. Headspacing can be a dangerous issue though and it's recommended you stick with the bolt/barrel of the same type. . The barrel nut though has me wondering what's up. At this time, I'm just waiting to see.
Armalite AR-10 barrel nut threads are 1-7/16” and 18 TPI-3A
DPMS pattern barrel nut threads are 1-7/16” and 16 TPI- 2A
But that is the internal threads, not the external. If they are using an external thread for Armalite handguards then that's very possible. As the DPMS system has about three different heights. But... the external thread doesn't mean anything with regards to the barrel. So... is it in fact Armalite pattern or just fits ARmalite compatible handguards. Could be DPMS internal threading and Armalite external handguard specs? Which would make it in fact a propriety barrel nut. Not uncommon with AR308 rifles. At this time. I really don't know.
