Heckler & Koch MR762 A4, 7.62 NATO, 13″ Threaded Barrel, Black, Ambidextrous Controls, 20 Rounds

The HK MR762 A4 is the definitive civilian 7.62 NATO short-barreled rifle — a direct descendant of the HK417 battle rifle that has served with the world’s most demanding special operations units. At 13 inches of cold hammer forged barrel and 8 pounds, the MR762 A4 is what HK engineers consider the optimal balance of 7.62 NATO ballistics, handling in confined spaces, and the reliability that defines the H&K brand. This is not an AR-10 variant. The MR762 A4’s short-stroke gas piston operating system, manufactured to the same tolerances as its military counterpart, delivers a level of reliability, barrel life, and fouling resistance that direct-impingement 7.62 rifles fundamentally cannot match.

The A4 represents the most refined iteration of HK’s MR762 platform — updated with a full-length M-LOK compatible handguard, ambidextrous controls across every critical function, and an adjustable two-position gas regulator that transitions seamlessly between suppressed and unsuppressed operation without changing ammo or adjusting dwell time manually. For a shooter adding a .308 suppressor to this platform, the engineering is already there: thread the suppressor on, flip the gas regulator, and the MR762 A4 runs with the same cold-blooded reliability it does without one.

HK MR762 A4 SBR Specifications

Why Gas Piston Matters: HK’s Engineering Advantage

Direct-impingement AR-10 and AR-15 pattern rifles route hot, high-pressure gas from the barrel port directly back through the bolt carrier group — depositing carbon fouling into the action with every shot. Over a magazine or two, the fouling accumulation increases friction, reduces reliability margins, and requires more frequent cleaning. HK’s short-stroke gas piston system routes that same gas into a piston that operates the bolt carrier without direct gas contact. The bolt carrier stays cooler, cleaner, and runs longer between cleanings with greater reliability margins. For a suppressed SBR running 7.62 NATO — where gas pressure is higher and fouling more aggressive than in 5.56 — the advantage of piston operation is measurable and meaningful in field conditions.

The Adjustable Gas System for Suppressed Use

The MR762 A4’s two-position gas regulator is specifically designed for suppressor use. Position 1 (normal): optimized for unsuppressed fire. Position 2 (suppressed): reduces gas volume fed to the piston, compensating for the increased backpressure that a suppressor introduces. Switching takes less than a second. The result is reliable cycling with a wide variety of .308 suppressors without the over-gassing, increased fouling, and accelerated wear that unregulated gas systems experience when running suppressed. HK engineers this from the factory — it’s not an afterthought.

Cold Hammer Forged: HK’s Barrel Standard

HK has cold hammer forged its barrels since the company’s founding. The process uses hardened steel hammers to forge the barrel around a mandrel, compressing and aligning the steel’s grain structure for greater hardness, better surface finish in the bore, and dramatically longer service life than button-rifled or cut-rifled barrels. HK’s specification for its cold hammer forged barrels is 20,000+ rounds of service life — a figure most alternative manufacturing methods cannot approach. On a 13″ 7.62 barrel that will see suppressed use (higher pressures, higher temperatures), HK’s barrel longevity is a genuine long-term value proposition.

Why Buy From Western Sport?

Western Sport is a licensed FFL/SOT dealer in Roanoke, Texas — an experienced NFA dealer serving North Texas since 2007. Our team handles every aspect of Form 4 SBR transfers: paperwork, fingerprints, ATF submission, and follow-up. We stock premium NFA firearms because we believe in helping customers access the best defensive and precision tools available. Call 817-393-4000 to discuss this or any other NFA firearm. We ship to your local FFL anywhere in the continental US.

Frequently Asked Questions — HK MR762 A4 SBR 7.62×51

How does the MR762 A4 compare to an AR-10 or DPMS-pattern 7.62 SBR?

The MR762 A4 uses HK’s proprietary gas piston system rather than direct impingement. This means significantly less fouling in the action, a cooler bolt carrier, longer service intervals, and proven reliability under sustained and suppressed fire. AR-10 pattern rifles offer lower prices and broader aftermarket parts availability; the MR762 A4 offers HK engineering, cold hammer forged barrel, and piston reliability at a premium price point that the most demanding applications justify.

What suppressors are compatible with the MR762 A4?

Any suppressor rated for 7.62 NATO and threaded 5/8×24. Popular pairings include Sig Sauer SLX 762, Daniel Defense SoundGuard, and Q Tall Boy/Thunder Chicken. The MR762 A4’s two-position gas regulator simplifies tuning for suppressed use. Contact Western Sport at 817-393-4000 for current in-stock suppressor pairings.

What magazines does the MR762 A4 use?

HK417-pattern 7.62×51 magazines. The rifle ships with a 20-round steel magazine. STANAG-7.62 (SR-25/HK417 pattern) magazines from Magpul, HK, and other manufacturers are also compatible.

Is the MR762 A4 SBR different from the MR762 pistol configuration?

Yes — the SBR version is registered as a Short Barreled Rifle under the NFA and transfers via Form 4. The pistol configuration sells without NFA restrictions but is functionally similar. If you want a collapsible/folding stock (which requires SBR status), this is the NFA-registered version. The $0 stamp under OBBBA makes the registration cost negligible.

How long does the NFA transfer take for this rifle?

about two weeks or less for ATF Form 4 approval. The process: purchase, complete Form 4 with Western Sport, submit fingerprints and photos, pay $0 NFA stamp (OBBBA has eliminated the fee), and wait for ATF approval. Western Sport guides you through every step — call 817-393-4000.

Recent eForm 4 approvals have been coming back in about two weeks or less — see our NFA wait times guide for current figures.