I got mine a week ago, and shot it for the first time, yesterday. It really is a beautiful rifle. Beauty is, as beauty does, right?
The elevation markings on the rear sight appear to be based on historical fidelity, rather than useability. To get the rifle on paper at 20 yards, I had to set the rear sight for 700 yards. It's not really an issue, other than the sight stands very high on the gun already, and appears sort of exposed when set for high elevation. The sight also had to be cranked way to the left to get rounds centered on target.
Sight-in consumed 30 rounds of Federal and CCI ammo, and the gun ran fine.
The baptism by fire was a steel-plate match, shot at distances of 20-60 feet. Not really accuracy intensive, as the smallest targets were 8" plates.
I started having functional issues, almost from the first match stage. Each of the six courses of fire required a minimum of 30 rounds, and in the first four CoFs, I don't know that I was able to fire even twenty rounds in a row without a malfunction. I'll provide one example: After completing a CoF, on the unload command I removed the mag and a live round fell out of the magwell. I retracted the bolt, and found a spent case in the port, and a live round in the chamber! It went like this for about 100 rounds.
Then, I got through the last two CoFs - 50 rounds - without a single functional issue, so maybe it was the much cussed/discussed "break-in" in action?
One problem that existed throughout the day, was the gun's inability to extract live rounds. I suspect the gun would run OK without an extractor, as some blowback rimfires do, but when it came time to unload the gun, I was picking-out the live round with my fingernail.
The gun is very fun to shoot. It's heavy - well over nine pounds - but the weight is between the hands, so it doesn't feel heavy or clunky. The thumb safety works "backwards", rotated by the thumb (right-handers) through a fairly long arc, up and to to the rear for "fire". Applying the safety is an easy, down/forward rotation.
The trigger is OK. It has fairly long travel, but it's not heavy, rough, or with any stacking or staging.
I am so accustomed to shooting with ghost ring/peep style rear sights, that the Stg sights took some real getting used to; a vee notch and pyramid front, but they were very usable for quick shooting at close range.
Claw-style scope mounts for HK rifles will apparently mount on the Stg without issues, but those that I've seen mount the scope much too high to get any sort of cheek weld while shooting. A mount that I saw in Shotgun News appears to locate the scope rail close to the top of the receiver, but I haven't seen any pics of that rail mounted on anything.
I'll strip/clean/inspect the gun today, and see if there's anything obviously wrong with the extractor. I certainly don't fancy sending the gun back to Germany for repair; does ATI have a U.S. repair facility?