Builds Blog Volume 3 | Chris' 6ARC

The 6ARC cartridge has quickly become a disruptive force in the AR-15 world, offering shooters a rare combination: greater consistency at distance with no sacrifice to weight or handling. By leveraging high-BC 6mm projectiles, 6ARC retains energy further downrange, delivering improved wind performance and superior terminal ballistics.

This build centers around my opportunity to unveil the new Noveske DDF 6ARC barrel, a heavy-profile 14.5” core that anchors the rifle. In my opinion, 6ARC is the ultimate evolution of the SPR/GPR concept for the prepared citizen. It's positioned as a legitimate contender to replace at least one of your 5.56 rifles.

Build Philosophy and Intent

This rifle was purpose-built to remain compact, suppressed, and optimized for long strings of fire typical of a GPR or SPR role. I prioritized reliable suppressed function, heat management, and seamless tripod use thanks to a rigid, integrated ARCA rail.

Key Components

Barrel: Noveske DDF 14.5"

The deep-fluted profile saves weight without sacrificing rigidity or surface area. While I have not measured thermal performance scientifically, this barrel runs noticeably cooler and holds tight groups even when hot, a must for an SPR built for sustained engagements.

Gas System and Suppressor Tuning

This rifle is built from the ground up to run suppressed. I used a BRT custom gas tube with a 50/50 port that restricts excess gas while avoiding the complexity of an adjustable block.

The suppressor is the CAT NOAH (Chris shilling for CAT again), which is my go-to for 6 ARC. Made from 718 Inconel, it balances sound suppression with minimal back pressure, a key factor since 6 ARC powders are notoriously dirty.

Proper suppressor selection is not optional on this cartridge. High-back-pressure cans introduce fouling and accelerate bolt wear. The NOAH keeps the system clean and reliable without sacrificing suppression. The suppressor rides on a Diligent Defense ZILCH hub mount and DD CBAH muzzle device, a pairing that reduces length and improves blast baffle performance. For a thermal cover, I selected the Liberty’s Defense Straightjacket, a rugged choice that shrugs off heat where lesser covers fail.

Rail: Ripcord LDRA 13"

This rail is a personal favorite. Its rigidity, integrated ARCA section, and tight tolerances help minimize point-of-impact shift, which is a non-negotiable trait in a true SPR.

Receivers, BCG and Buffer System

The upper receiver is a SOLGW. The lower receiver is an Aero Precision. Nothing fancy, just reliable. The bolt carrier is a Microbest chrome carrier, paired with a Noveske 6 ARC bolt that ships with the barrel. The bolt is a critical component due to the increased case diameter, and Noveske has engineered a robust solution. Microbest is also a sleeper brand in terms of performance. Austin and I both run them on our SPRs. They come with all the details and QC you expect from big-name brands, but come in at almost half the price, depending on what model you get. Buffering is handled by the VLTOR A5 system, my preferred configuration for SPRs, mated to a Forward Controls Design A5 receiver extension for refined adjustment and improved fitment. Once again, all of these choices are very similar to what you saw with Austin's SPR.

Optics and Mounts

The primary optic is a Leupold Mark 5HD 3.6-18x PR2 in a Leupold mount, with an Aimpoint ACRO P-2 mounted at 12 o’clock (missing from the photos, we had some testing of stuff we can't show you yet). For leveling out the rifle at distance, I also run a Flatline Ops Bubble Level. The ACRO is perfect for close-quarters and night vision-compatible aiming. This optic setup balances lightweight glass with excellent reticle functionality for distance work while providing a rapid target acquisition solution for CQB.

For the protection of the optics and signature management, I'm running our new Ruggedized ScopeCap Pro™ on the front and Ruggedized Rear SceopCap™. We took everything you liked about the originals and made them even tougher, with improved materials and refined fitment for better durability in rough conditions. Whether you are crawling through brush or running your glass hard in field environments, these are built to stay put and hold up where standard caps fall short. They’re available now and ready for whatever abuse you throw at them.

Stock, Ergonomics, and Fire Control

The stock is a Magpul SL, chosen for its slim profile that better fits my face and works well in the field. A Subrev Bag Rider improves rear bag interface, correcting a common flaw in many carbine stocks. The trigger is a Geissele SD-E for a clean break and reliable reset. The grip is a Driven Arms Co SCG, offering excellent hand-filling comfort that improves overall ergonomics.

Final Thoughts

This 6 ARC build represents what I believe to be the next logical step for the prepared citizen who demands greater reach and consistency from an AR-15-sized platform.

In a world where flexibility and capability are paramount, a lightweight platform that can confidently reach to 1,000 yards while delivering nearly double the energy on target compared to 5.56 is a true force multiplier.

Thinking about building your own 6 ARC? Every component in this rifle was selected for reliability, performance, and longevity in the hands of a capable shooter. When done right, 6 ARC does not just extend your range, it fundamentally expands your capability.