San Tan Tactical , Hornady Mfg and Proof Research New 6ARC (Advanced Rifle Cartridge) STT-15-6ARC Rifles


CHANDLER, ARIZONA: San Tan Tactical®, Hornady Mfg® and Proof Research® have partnered up on the San Tan new 6ARC rifles. San Tan’s innovative high quality firearm systems and unparalleled performance in combination with Hornady’s New 6ARC round originally developed for a specialized group within the US DoD, and Proof Research premium carbon fiber barrels take the AR15 platform to a whole new level!

The Hornady 6ARC Round

Hornady Mfg® a leading ammunition manufacturer, provides world-class performance in a 6ARC factory- loaded cartridge. The high-performance, match-accurate round features an excellent cartridge-to- chamber relationship and shoots exceptionally well. The 6ARC is commercially available in 108gr ELD- MATCH, 105gr BTHP BLACK and 103gr ELD-X -Precision Hunter loads. The ELD-Match round boasts a G1.536BC.

6mm ARC Advanced Rifle Cartridge





Tested, selected and fielded by a specialized group within the US DoD for its multi-purpose combat rifle program, the 6mm ARC is an extremely versatile cartridge that does everything much larger cartridges can, and everything that smaller cartridges can’t. Designed to meet the demanding needs of the world’s toughest critics, the 6mm ARC is a truly advanced cartridge capable of utilizing high BC, efficient 6mm bullets for unprecedented levels of performance from such a compact platform.

Advanced–Purpose built to achieve performance never before delivered from the AR-15 platform by providing the ultimate blend of system weight, performance and shootability.

Versatile-Equally at home in AR-15 platforms and short or micro action bolt guns and suitable for a variety of applications from personal defense, match shooting, hunting as well as military and law enforcement use.

Efficient –Balanced application of cartridge and chamber geometry & interface, propellant design and bullet selection for optimum performance and barrel life, the 6mm ARC has unmatched long- range performance from the AR-15 or micro action platform.

Effective–Excellent terminal performance from an assortment of bullet selections, for a variety of applications.


–Features match accurate Hornady bullets that are held to the tightest tolerances in our test lab. Low recoil

-Utilizes an efficient propellant charge and bullet weight combination.

-Self-spot impacts on or off target to make rapid adjustments.

-Less felt recoil than larger short action based (308 Win family) cartridges.


-Factory ammunition offerings in a variety of bullet styles may be complemented by the handloader who has a multitude of 6mm bullets to choose from for specialized applications from varmint and deer hunting to match shooting needs

81608 6mm ARC 108gr ELD-MATCH

Muzzle Velocity = 2750FPS with 24″ test bbl G1
BC = .536
SD = 261
Min Twist Rate = 1-8”

81604 6mm ARC 105gr BTHP BLACK

Muzzle Velocity = 2750FPS with 24″ test bbl G1
BC = .530
SD = 254
Min Twist Rate = 1-8″

81602 6mm ARC 103gr ELD-X -Precision Hunter

Muzzle Velocity = 2800 FPS with 24″ test bbl
G1 BC = .512
SD = 249
Min Twist Rate = 1-8

The Proof Research® 6ARC Carbon Fiber Barrel

The STT-15-6ARC and STT-15-6ARC-Lite both are configured with industry leading Proof Research® Carbon fiber barrels. Known synonymously for their quality, ultra lightweight characteristics and superior accuracy. Featuring a 6ARC Chamber,18” Length, 7.5 Twist, Rifle gas, .750 diameter gas block.


The San Tan Tactical STT-15-6ARC rifles are a superb example of industry leading technologies from companies pushing the envelope with a desire to achieve more! With the other wildcat caliber’s coming to market over the recent years, the recent 6.8 military requirement, all in an attempt to pursue the maximum output from the AR15 platform.

The Hornady 6 ARC cartridge combined with their variety of projectiles currently available allows a significantly increase in capability above and beyond what is currently available in the AR15 platform. The capability to weight savings is seen in out STT-15-6ARC-Lite, the slick sided billet matched receiver set with out signature lightening pillar cuts. Removing as much weight as possible without sacrificing strength and performance.

STT true matched pillar billet sets, hand finished, matching serial numbers. The upper is cut from a single solid 7075T6 Certified Aerospace Aluminum. Propriety special burnished bore that gives a compacted internal surface, resulting in a much smoother surface finish. The bore, receiver extension face, barrel nut threads and barrel extension surfaces are all machined in one operation ensuring that they are perfectly concentric and perpendicular to the barrel assembly.

STT Lower Features:

• Huge 1.38” Integrally Machined Magazine Well Flare

• Ambidextrous Quick Attach Detach Sling Swivel Points with Anti-Rotation Stops • Ambidextrous Bolt Release

• Ambidextrous Magazine Release

• Bullet Pictogram Safety Selector Markings

• Set Screw Trigger Creep Adjustment

• Set Screw Upper Take Down Tension Adjustment

• Shooter Ready Finger Rest

• Oversized Winter Trigger Guard Perfect for Gloved Hands • Dowel Screw Assembly

• Ultra-Grip Texture on All Controls

STT Upper Features:

• San Tan Tactical Truss Pockets for Increased Structural Rigidity

• Cut from a Single Billet 7075 -T6 Aerospace Grade Aluminum

• Shell Deflector

• Fully Assembled with Forward Assist & Ejection Port Cover

• Machined in T Markings for Easy Optic Relocation

• Machined with M4 Feed Ramps

• Machined to Mil-Spec Standards

• Interfaces with all AR15/M16/M4 Systems & Accessories

• Compatible with Multiple Rails, Anti-Rotation Tabs & Pins

• Compatible with All Known Battery Levers

• No Roll Pin Design – Forward Assist Attaches Via Threaded Dowel Pin

San Tan Tactical STT-15-6ARC Rifle Features:

• STT Suppressor Optimized Enhanced Bolt carrier group

• STT 6 ARC HPT MPI Bolt, Crane O-ring Upgrade

• Proof Research 18” Carbon Fiber 6ARC Barrel

• CMC Triggers 3.5lb Single Stage Match Trigger

• MagPul MOE plus Grip

• MagPul CTR Stock

• MagPul MBUS Pro

• STT 15 16” MLOK Rail

• Precision CNC machined from billet 7075-T6 certified aluminum

• Propriety special burnished bore that gives a compacted internal surface, resulting in a much smoother surface finish

• Type 3, class 2, deep black, hardcoat anodized black

• Features extended feed ramps

• Ambidextrous Mag and Bolt release controls (ambi version only not Lite) • CERAKOTE options are available for additional cost

At San Tan Tactical we want to leave a proud legacy of American Made firearm design. By innovation, superior performance, and value. American Made, through and through is the core value at San Tan Tactical. San Tan Tactical wants each and every shooter to be completely satisfied! Giving them absolute pride of ownership in each product we design and manufacture.

Our formula for success is simple-

San Tan Tactical believes in America, and the heritage upon which this great nation was built! We are a company owned and operated by American’s for American’s! We only utilize the finest quality American made machine’s in conjunction with the highest quality American made materials. At San Tan Tactical we pride ourselves to give unparalleled customer service by, listening, understanding, and quickly satisfying our shooters needs, desires and/or concerns.

San Tan Tactical will never forget that our future success depends on the legacy of our past. We are not satisfied until you are satisfied!

All STT products come with a Lifetime Warranty and are made in the U.S.A., STT proudly designs all its products for Law Enforcement, Military and Civilian use.

For more information about San Tan Tactical and all the products we offer please visit us at


    • Eh, not really. The .243 doesn’t have enough neck length, and uses a larger diameter case than this does. The .243 is a .308 necked down to 6mm. This cartridge appears to be based off something similar to the .220 Russian.

      This is like a 6mm PPC with the shoulder blown forward for a skosh more capacity – that’s it. They might as well have made a “6 PPC-AI” for all it is going to do.

      The 6PPC gives pretty good barrel life. The .243 Winchester can burn up barrels in a short time. That’s something that lots of .243 shooters discover only when they start using a .243 for target shooting – the .243 is up there with the 6.5-284 in overbore, and I’ve seen .243’s with serious throat erosion in about 1800 rounds. Part of the problem is that the .243 gives shooters enough case capacity to stack a stupid amount of powder behind a small bore diameter. Part of the problem is that most .243 shooters are shooting light bullets at holy-crap velocities for varmint shooting.

      The 6PPC is a cartridge that was developed for target shooting – specifically. Not varmint shooting, not hunting, not nothing. Punching holes in paper at up to 300 yards was the intent. They did a good job at it. It’s slower, cooler, smaller than the .243, has a longer case neck so you can seat really long bullets in it. These guys are trying to make a “6PPC-Plus.”

      • the new round’s performance will be comparable to a 243. I am aware of the history of the 243 WCF and it’s performance. You would be hard pressed to find some one who has used the 243 more or owned as many and been a bigger fan of the 243 than I am. Outside of Warren Page and he’s dead.

  1. So, let me get this straight:

    It appears that their parent cartridge design is quite nearly the .220 Russian… but… they moved the shoulder forward to increase case capacity a bit, reduced the case length base-to-neck a bit, and by so doing, they’ve reduces the ability to use longer 115 grain low-Bc bullets. Brilliant.

    The 6PPC is a benchrest cartridge that’s been around since the 1970’s that has laid down records for group size and consistency, and they expect people to fawn and gape over this new development? They could have standardized the 6PPC, and leveraged off all that work that has been done to get groups under 0.010″ at 100 yards, but instead they chose to do this, so all that work has to be done again?

    Presumably, they did this so they can have some pneumatic blonde pose with their new tacti-kewl AR in this boutique cartridge at the SHOT show, right? I mean, you can’t get press without a wholly new cartridge that’s being fawned over by youngsters who have no idea that there were accuracy rifles made before the AR, right?

    C’mon. This is just boob bait for young bubbas who refuse to stick their noses into the benchrest world, because they think that old men know nothing.

    By the way: The hot bullet for accuracy work in 6mm is the 115 grain DTAC. Has been for years and years. They’re giving up Bc to go with the lighter bullets.


      • I imagine the results were a disappointment – like everything else that came out of the Mini-30 line of products. For some reason, those rifles don’t produce a “group” downrange, they produce a “flock.”

  2. “Tested, selected and fielded by a specialized group within the US DoD for its multi-purpose combat rifle program…”

    So this was rejected by some agency or department and now they’re marketing it to the citizenry?

  3. It seems a little like the 6mm Rat, but the body is not blown out as straight and the shoulder not blown as far forward nor as sharp. The Rat is based on the 6.5 Grendel so in the neighborhood of the 220. I’ve been shooting the Rat “across-the-course” and it seems pretty good for that purpose. Case life has been very good, but I don’t hot-rod my loads either. I shot a 200-14X at 600 with Berger 105 Hybrids with it the first time out and I’ve been trying to live up to that ever since.

    If a guy was intending to shoot out to 1-K or beyond there are better choices, but I expect this would be a good choice for somebody wanting a 6mm gas gun for XTC purposes.


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