So I built this over the past year + and after finally coming home, I have completed it. This post was originally started on the 68forums but I also wanted to share here as I had been talking to TECHUSMC on here when I started building it.
I went with the following and in choosing the OPS 416 kit some slight modifications/tweeks were done.
Prices were from the time of purchase and may have changed since.

6.8 SPC II AR Build
Barrel: AR Performance 16" 6.8 SPCII Scout profile barrel- 4150 CMV $175.00
Muzzle Break: AAC Brakeout 2.0 FSC 7.62 51T 5/8X24 $88.00
Barrel Nut: Aero Precision AR15 BAR Barrel Nut #APRH100268 $36.00
Hand Guard: Aero Precision 12" Enhanced M-Lok Hand guard #APRA100017C $157.50
Pistol Grip: ERGO GRIP SUREGRIP #: 4000-BLK $26.40
Upper: Aero Precision AR15 Stripped Upper Receiver #APAR501603B $44.00
Lower: Aero Precision AR15 Stripped Lower Receiver, STS #APAR501103B $75.00
Parts kit – Upper: RRA AR15 Upper Parts Kit #RRA-AR0048K $22.90
Parts kit – Lower: Aero Precision AR15 Lower Parts Kit #APRH100029 $54.00
Trigger Guard: Aero Precision Trigger Guard #APRH100084 $18.00
Bolt: AR Performance 6.8 SPC AR15 M16 bolt #471263987 $85.00
Firing Pin: VooDoo Innovations Firing Pin Stainless Steel LifeCoat $18.00
Gas Block: Geissele Automatics 05-231C Super Gas Block Carbon Stl $50.24
Charging Handle: BCM Charging Handle Mod 3 Lrg Latch $42.18
Gas Piston kit: Osprey Defense OPS-416 Rifle Length Kit $185.00
Gas Tube Op Rod: Osprey Defense Free Float Op Rod ARK-INV5266 $43.50
Butt Stock kit: ACE Ltd. ARFX Skeleton Stock Assy Kit+ Buffer Spring/Tube $110.00

TOTAL: 1230.72 ( I also had to add approx $150 for the smith work and Cerakote job).
All in all I think I am into the rifle (minus Optic) for around $1500.

Here is the complete Cerakoted Rifle.





Here is the Gas Block, I went with a Geissele Low Profile Gas Block and had it pinned due to some reports of the piston actually pushing the block forward over time.
With the help of Mr Penty Wheeler, we did have to open up the gas ports to match up the Geissele Lo Pro gas block and everything cycled perfectly at .080"







I will say that you are limited on which Hand guards you can use when deciding on the Ops-416 Gas Piston kit but if you look, more and more are available. I went with an
Aero Precision AR15 Enhanced Hand guard which gave me a 1.8" inside diameter. This would also give me the option, if I chose to SBR it, to have the can inside the HG.



The optic I went with is a Vortex Viper PST 2.5-10x32 FFP mounted on an Aero Precision Ultralight 30mm Scope Mount.

I will be hitting the range shortly and I can update on how poorly I shoot :)

Cheers folks,

TX

Looking forward to the range report!

So today I hit the range out in Garland,TX. Its an indoor range and mostly I just wanted to test out the OPS 416 and sight in my optic. Well,,,,,,,,,,like always, plans change as the unexpected happens.
I had picked up a couple of boxes of Hornady 110gr V-Max 6.8SPC ammunition as I have had good experiences with this round in the past. I loaded three rounds in my magazine for the first grouping, loaded the first round - steadied my aim and squeezed the trigger. BAM. Noted the POI and steadied for the next shot.
Hold up a sec, I didn't see or hear any brass expelled...... Safed the rifle and dropped the magazine, one round left in there. Looked at the ejection port and here is what I saw:



I cleared the chamber and extracted the brass. Tried another round and the same thing happened. Extracted that brass and packed her up.

Now, I would like to note that after my smith friend had adjusted the gas port we test fired a magazine - 30 rounds with no FTF or anything. 30 rounds in a steady decent pace with no issues. I am waiting to see from him what ammunition he was using but it looks like my extractor failed to extract.

Any thoughts?

Cheers,

TX

So after inspecting the brass as well as the extractor, nothing was out of spec. Checked Go/NoGo guage and the bolt seated with the go gauge and then also seated with the no go gauge. I don't have a field gauge for 6.8 SPC II but Seating with the NoGo gauge doesn't necessarily indicate a problem. Decided to polish out the chamber and attempted to recreate the problem without the firing pin in the bolt. Everything cycled fine and rounds were extracted no problem. Now I assume that with the expansion of the brass when fired, this was possibly causing the issue (unknown) but we went ahead and test fired a few rounds and nothing failed to cycle, or extract as well as chamber a new round.

Tomorrow I plan to go out and field test with a few boxes of ammunition and will report what we find.

Cheers

So today was the big test. Seriously crappy weather out here but after Penty did some polishing of the bore, we started out shooting some more of the Hornady 110gr V-Max 6.8SPC ammunition. Initially slow shots and checking everything like cycling and feeding. Worked like a charm. Next she ate some Federal 6.8 SPC 115gr Fusion MSR Ammunition without a hickup!. Then finally it was a mix and 2 magazines dumped through in quick succession. No failure to fire, extract, chamber or feed any rounds. Quite happy to say the least.

Next I will be sighting in that optic and seeing what we can do with it.

Cheers folks.

TX_Grubby

Good to see it worked out better today.  Keep us posted.

Nice looking carbine!

very happy to see the OPS fits inside the m4e1 handguard, as I just picked one up for my osprey build.


eta: just wanting to confirm, other than running the modified length oprod and opening up the gas port, you didnt need to make any modifications to the handguard/barrel nut/upper receiver to get the system to fit, correct?

Other than what was listed I DID shave down the Op Rod locking pin as seen here



It wasn't that it was catching, but was close enough that I decided to dremmel it down.

Now for the barrel nut, I used the Aero Precision one on a threaded AP upper



It was cool to build and is starting to get enjoyable to shoot LOL

Holler if you have questions. Also, One thing I want to add is that my Ops 416 kit was a rifle length so I cannot confirm what the difference in port sizes.

Cheers