H&K has a specially designed match barrel and a few other differences from a standard AR-10 according to an article I read. Like everything H&K it is expensive but top notch. If I recall right there was a competition and this rifle won.
If you want one that is less expensive and just as good look at the SIG716DMR. Their 716 and 516 series was designed by the same dude who was on the design team at HK. Their systems are not much different.
Yup! and more prone to a variety of stoppages, too. I'd quote Professor Ryan E. LeBlanc's scholarly thesis on this subject; but, alas, it's been pulled off the internet; i.e.: Original internet publication. Now, anybody who wants to read (and learn) about this topic is going to have to pay for the information, like, maybe, from Google Books. I have a copy of this work available for my own use; it's very informative; and I have also quoted significant sections of the original manuscript (with proper accreditation, of course) in a technical article I wrote for publication; but, as luck would have it, my work is also copyrighted as soon as it is submitted; and I'm unable to share my own several thoughts on this interesting topic. Anyway, it's a sniper rifle with an, at best, modest duty cycle and rate-of-fire; it isn't going to get too hot, or too crapped up; and the short piston, most likely, won't be subjected to heavy mechanical stress. H&K should be OK with their new M110A1's mechanical platform. It's pricey, though; and, in a combat zone, I wouldn't want an M110A1 to be my only long arm. (Believe it, or not, Eugene Stoner put more thought into the M16's original DGI design than he's often given credit for!)
The real question if anyone is actually interested in an overpriced HK is what country they make it in. If its made in Germany you may as well look at something else. HK is alot like FN or Styer. Most of what they make never sees civilian eyes. Another good question is what can a proprietary, semiauto, AR10 style rifle do that any other AR10 style rifle wont. I think the answer is not much and definitely not 10 grand worth.
Long Range Acurate shooting is a lot more about the Ammunition, and Shooter, than the FireArm used, once you get a Sub-MOA Weapon... Charactoizing the Barrel, and finding the “SweetSpot” Loading for that Barrel/Projectile Combination, is where the time needs to be spent... It took a couple of hundred rounds at 1000 yds, to get the first Loading for my custom built DMPS AR10 w /24” Stainless Bull Barrel... The second Loading with a different Projectile only to abut 75 Rounds... Stll working on the Third Loading... Windless days are few and far between in the fjords of Alaska during the winters, and to many folks roaming around in the summers...