I was able to get out over the weekend and get the 556R w/ ACOG sighted in.
Fired about 75 rounds during the outing, the rifle made it through 75 cycles of operation (feeding, chambering, locking, firing, unlocking extracting, ejecting, cocking without issue. Spent casings were flying out of the gun.
I mentioned some dislikes about the gun in the previous posting, the safety lever is definitely too small. A Krebs aftermarket lever will be added later. I am unsure if I will be replacing the grip at this time or not, but a slimmer grip option would be nice.
The lack of iron sights on this rifle is baffling, I don't know what Sig was / is thinking. Sure we all like optics and that is probably the first thing most people add to a rifle/carbine these days, but sending out a $1K+ rifle without usable sights is just stupid.
The trigger is heavier, but pretty smooth. The stock will be getting changed out eventually to give me a better length of pull, it's a little short as is for me.
Accuracy-wise, I'm pretty happy with it and the Wolf Military Classic 124gr FMJ I was shooting. 3 shots touching @ 100yds with a 3X ACOG near the end of my trip and my eyes were getting fatigued. I need to explore a different optic that will allow my cross-dominant self to shoot with both eyes open, by the end of the outing my right eye felt majorly fatigued. Nothing stellar, but it will do the job.