Finally got one of these before the long weekend. I've been making empties by the bag with it.
Like every American i have had my hands on, the one complaint is the damn stock. From the factory, the barrel touches the left side of the stock channel. On the Predator i had, i relieved the stock and it was fine. On this one, i was able to position the stock and re-torque it. The "power bedding" block seems to be holding it in place. Ruger needs to check their jigs or something.
Mine seems to favour heavier bullets. Best groups have been with 75grn loads. Accuracy is plenty good for what it is. I may bed the stock... just for giggles.
The nature of the AR mag and magwell seems to dictate running the bolt briskly. I like that. Extraction an ejection has been perfect. Cheap plentiful mags are a bonus. If there is one downside to this, it's that single loading isn't a thing. The follower keeps the bolt from riding forward (last round BHO. ). Best to just slam in another mag and keep going.
I've tried at 4 or 5 different brand mags, zero issues. As long as the bolt is all the way back when inserting with it open.
Light, handy, accurate enough, and fun to shoot. It really is the AR of the bolt gun world.
Oh, and mine is marked 5.56