H&K MR556-SD MR762A1-SD with Modular Rail System & OSS Suppressors

Rob Curtis published a product brochure for the upcoming not-yet-announced H&K MR556-SD MR762A1-SD. The H&K MR556-SD MR762A1-SD features a new Modular Rail System (MRS) that allows rails segments to be screwed in where required, much like the KeyMod system. The suppressors are interesting. Rob writes

The OSS suppressor system also improves the HK platform by adding caliber and configuration modularity, individual suppressor component sustainability, greater than 90% reduction in blowback and bolt velocity compared to competing suppressor systems. The OSS system comprises a back pressure regulator (BPR) and a sound reduction module (SRM). The rifle is shot ‘unsuppressed’ with the BPR installed. This reduces flash and noise noticeably, but the addition of the SRM will reduce the muzzle noise to 139db at the shooters ear.

These guns will be available for sale to consumers.


Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Aric

    Are the keymod holes backwards?

  • Harrison Jones

    The backwards keymod rail makes no sense. They should have used the keymod system to conform with the rest of the industry. Besides that it looks like an interesting system.

  • k

    “These guns will be available for sale to consumers.”

    lul, ill believe that when I see it, oss suppressors are like unicorns

  • Mandaloin

    “These guns will be available for sale to consumers.”

    But at what cost?

    • No idea yet. We’ll probably find out at SHOT

    • Beju

      FWIW, a MR556A1 has an MSRP of $3295, a MR762A1 has an MSRP of $3995, and the only price I’ve seen on an OSS BPM and SRM was $1495.

      Call me a pessimist, but I don’t think H&K is going to offer a package discount.

      • Mandaloin

        Yeah I was implying these things will be cool but unreasonably expensive.

        • Beju

          I think that’s a safe assessment. H&K making an attempt to compete on price with even the expensive makers of comparable firearms, let alone the cheap ones, now that would be news!

  • Colin

    Why haven’t they used the normal Keymod system? Its free (no copyright) ffs, HK to redesign the wheel next too?

  • IXLR8

    You had me at H&K….

  • KestrelBike

    I just really wish suppressors were no longer NFA items : ( Such a pointless political bogeyman. That said, I *LOVE* how often suppressors are in the Firearms news, media, etc these days. More and more exposure can only lead to good things in terms of bringing public attention to the fact that they’re not baby-murdering tools.