Assembled from a Bravo Company M4 upper and one of AR Performance's superb 12.5" 5R 6.8mm SPC barrels. Comes with a properly headspaced NiB Superbolt also from ARP. I had an A2 front sight post taper pinned to the barrel but decided to go low profile and modified the fsb to fit under a free float handguard. It will fit under an ALG rail and probably others but will be tight in some of the super slim rails. Might need further modification. Regardless, I really like it being taper pinned. I test fired it using 115gr Federal AE and it cycled perfectly with a Barrett and ASC magazine. Empties landed between 3 and 4 o'clock using a standard carbine buffer, spring and M16 carrier. Upper is complete except for charging handle and carrier. You get the barreled upper with bolt only. No muzzle device but I will include the thread protector. Fit is perfect with Anderson lowers.
About 100 rounds total through the barrel.
Asking $350 shipped. That's pretty much just what I have in parts. Nowhere near what I have in labor and time spent.
And to answer some questions. Yes, the gas block can be removed by just driving out the taper pins. Then you can install a true "low pro" gas block. You can't install a new front sight block and expect the pin holes to line up. FSBs are installed on the barrel when new and then drilled. If you try to install a new FSB on an already drilled barrel it will not line up correctly. You're just better off leaving this block as is or installing a low profile unit. Then you can go with a free float tube of your choice. But I think this pinned block will fit under a lot of rails out there. Just take good measurements before you buy.
For those concerned, 224 Valkyrie magazines also work for the 6.8mm. Makers include ASC, CPD, Barrett, PRI, D&H, E Lander, and a couple others I can't think of. So, don't let magazine availability concern you. No, you can't have mine;)