One of the great things about SF is the way you learn a lot of skills. For example, if you went to the old O&I school, you got an excellent and in-depth intensive course in taking first class documentary photographs. We regret that the old teammate who took these photos is not a graduate of that course. In fact, even though he’s now in the industry and was at SHOT, he was our team medic– and a very good one.
At the SHOT Show recently, HK’s new MR556-SD and MR762-SD, which exploit new suppressor technology from Utah-based OSS (Operators Suppressor Systems), caught his eye, and he snagged us a few cellphone shots.
We haven’t seen anybody else documenting the innards of this new development. So we’re going to do it — even though the photographs we have are less than fantastic. Discussing this new weapon with guys from the days of the old MP5SD, we thought that this might be a good replacement for that weapon, now that everyone uses carbines rather than submachineguns for CQB. The advantages of suppressors are pretty significant in combat.
We were less than shocked to discover the guys at OSS came out of SF and the Ranger Regiment, inter alia.
Here’s a look down the throat of the thing, we believe this is towards the muzzle end:
Here’s another interior shot:
Here’s a blurry look at the outside:
The nomenclature of the components of this suppressor will be clear enough, below.
What you’re Seeing in the Photos
The OSS suppressor has several unique design features:
Its exterior is octagonal, not round. (HK installs a rail to match on the SD versions). The octagonal rail spreads the rising heat to reduce mirage effect.
- It’s modular. (That’s the big buzzword of SHOT 14, isn’t it?). Part of this modularity is: it’s caliber convertible between 5.56 and 7.62 (or, presumably, other calibers). They also make a big-daddy that’s convertible from .300WM to .338LM.
- It’s self-tightening (can’t shoot itself loose), but can be removed by hand.
- The gas is turned back by a deflector, and then makes its way through the unit, gradually expanding, before being vented back towards the front of the suppressor and vented to the air.
The typical OSS suppressor has three components, the first is a Back Pressure Regulator which is available in two variations, BPR 1 actually fits back over the barrel and reverses gas flow (like a car muffler) and shortens length, and BPR2 mostly extends past the muzzle. The second is the Signature Reduction Module (SRM) which attaches to the nose of the BPR. The third component is the custom Flash Hider Muzzle Brake that is used to mount the BPR. The BPR can be run without the SRM — alone or with a standoff/flash hider device, but if one purchases the BPR and SRM at the same time, it’s a single serial number and single tax stamp.
- Pricing for the OSS suppressor on its own is quite reasonable. At the SHOT Show they were quoting ~$1500, but it’s not clear what HK will charge for the SD … yet. They do offer the OSS FHMB as standard on the new MR556 Competition Rifle at an MSRP of $2,947, so you’re looking at about $4,500 to have the equivalent of the SD. Will the factory SD command a premium, or sell for a discount?
- HK does intend to sell the SDs to civilians, with appropriate NFA paperwork. This is big. Thank you, HK USA. Maybe we don’t suck and they don’t hate us any more? Larry Correia, call your office.
They guarantee a 10,500 round life cycle for low rate fire if you follow their maintenance schedule. This is, to be blunt, unique in the industry. High rate fire? If you’re firing 3-5 round bursts at 850 rpm (typical for a piston AR like the HK416/MR556) you’ll see sound reduction degrade after 4,500 rounds. It’s user and armorer serviceable; the one wear part goes for $40, isn’t the NFA serialized part, and resets your wear to effective zero.
- They do not increase back pressure in the system. Again, unheard of. How did they do this? Well, part of the secret sauce is that they didn’t go for sound reduction to the point of interfering with weapons function. They went for -26dB (ear safe) rather than stretch for over 30 and run into reliability and maintainability issues.
So there is a tradeoff in going with the OSS suppressor. That tradeoff is biased towards benefits for the user that shoots a lot and cares more about tactical suppression than absolute stealth (OSS was founded by SF / SOF guys). After all, if you’re absolute-stealthin’ it, you’re probably not doing magdumps from an AR platform. If you’re mag-dumping with extant suppressors, including some quite decent ones like the issue KAC SOPMOD user or the AAC, you not only generate a lot of back pressure, you risk baffle strikes as the thing heats up. Those suppressors are built well enough to survive the baffle strikes, but what happens to accuracy is not good.
They explain the octagonal barrel quite logically:
The OSS Advantage is based on patented design technology that effectively manages heat & sound reduction while regulating back pressure on the weapon’s firing system. The octagonal external heat shield redirects the heat away from the top center-line of the barrel to a wider point, which moves the mirage from the center sight line of the optic. Every shooter appreciates a sight picture that is not blurry.
This is typical of the way the system is thought out with the end-user in mind. If you’ve used a suppressor like the decent Knight’s Armament Company unit on SOPMOD 1 guns, you’ve found the muzzle-heaviness and increased length forward at least a mild irritation. The BPR1 in particular doesn’t mess with your balance as much as traditional muzzle-attached suppressors do (this is one reason not-everybody runs suppressed all the time). It’s about 6 inches behind the flash hider, and .6 inch in front. But even the BPR2 only adds another inch or so in front. The SRM adds another 4.2 inches in front of the muzzle. The components are light; the BPRs under a pound each. We’ll take five inches and a pound-and-a-half forward to maintain our hearing in and after a firefight.
The HK integral suppressor guns are now catalog items, although the H&K website isn’t there yet. Soldier Systems has scans of the one-pagers on each, which we reproduce below.
Here’s a shot of the cutaway which we snagged off of HKPro, where it seems to have been second hand. Original photographer please let us know so we can credit and link you.
For more information:
This thread on HKPro gave me one image and a few facts about pricing of the OSS suppressor.