6mm ARC Precision Night Hunting Build: T&E Brief #1

Jul 29th 2025

6mm ARC Precision Night Hunting Build: T&E Brief #1

Rifle Build Breakdown

This season, I’ve put together a custom AR-platform rifle centered around precision, suppressed night hunting with thermal optics. Here’s the full breakdown of the rifle’s components:

Why This Build?

After a season of hunting with a 22" Ruger American Predator chambered in 6mm ARC, I was impressed by the cartridge’s flat trajectory and terminal performance. My handloads using 80gr Hornady ELD-VT over Leverevolution powder (in Hornady brass, with CCI 450 primers) yielded ~3150 FPS — absolutely devastating on everything from varmints to large boars.

However, the 22” bolt gun, with a suppressor, proved too unwieldy in a side-by-side. After dozens of climbs in and out per night, I knew I needed something more compact and nimble — hence the move to an AR platform. The trade-off? Sacrificing a bit of velocity for mobility and quick follow-up capability. My goal with this 13.9" barrel is to hit 2700–2800 FPS with a new load using the same ELD-VT projectiles, maintaining high BC performance with better handling.

Initial Impressions

Trigger – Geissele SD-3G

The SD-3G is incredibly smooth, with a rolling break and almost no wall. It's lightning-fast — ideal for fast follow-ups, which is crucial for predator hunting. That said, for slow, deliberate precision work, I personally prefer a trigger with a bit more wall. Depending on how it performs in the field, this trigger may find its way into a different style rifle.

Geissele Super Dynamic 3 Gun Trigger

Barrel – Sons of Liberty Gun Works 13.9" SPR

This barrel exudes quality. The bore and chamber are clean and well-machined, with a tight barrel extension fit. I had to heat the BCM upper to seat it properly — a testament to the thermal fit design. The pre-dimpled gas block journal is a nice touch for alignment. Be aware: it’s a heavy-profile barrel. Definitely not a lightweight hunting setup, but if you’re building a precision rig capable of maintaining accuracy under heat, this is the kind of profile you want.

Note: With a 13.5" handguard and 13.9" barrel, suppressor clearance is tight. I had to add extra shims to the direct-thread adapter to prevent the suppressor from touching the rail. For sub-14.5" barrels, I’d recommend going with a shorter handguard.

Bolt – JP Enterprises 6.5 Grendel

High-quality machine work as expected from JP. Time and round count will tell the full story, but so far, no complaints. Mated cleanly with the barrel extension and appears to lock up consistently.

Buffer System – A5 Setup

The combination of the Forward Controls Design A5 receiver extension, Sprinco Green spring, and A5H1 buffer has worked well for me in the past. I’m optimistic this will help tame the 6mm ARC, especially with the slower-burning Leverevolution powder and suppressor-induced backpressure.

Gas Block – Odin Works Tuneable

This block is a carryover from a previous build. Ironically, I never actually tuned it, so this will be the first time I really evaluate its adjustability. I may eventually compare it to something like the Superlative Arms block depending on how tuning goes.

Optics & Accessories

Thermal Scope – Rix Leap L3

I ran the Leap L3 all last season and was seriously impressed — especially for a 384-resolution optic. The ocular "zoom" feature (really just a zoom of the display screen via the ocular lens) is incredibly useful. It provides far greater clarity than digital zoom, and with the integrated throw lever, it’s fast and intuitive. One gripe: the battery door. It’s a bit finicky, and I’ve had occasional shutdowns after bumps. Hoping that gets sorted with different batteries or maybe a small mod.

Suppressor – YHM Resonator K

My first suppressor — and a solid budget pick. Sub-$500, HUB-compatible, and no frills. It's not titanium, but the weight and profile are manageable. It just works, and that’s really all I can ask.

Final Thoughts (So Far)

This rifle is purpose-built for night-time predator hunting: compact, accurate, and tuned for suppressed thermal work. While still early in the testing phase, fit and finish have impressed across the board. The key performance tests still lie ahead — gas tuning, load development, and real-world field time under thermal and suppression. I’ll post a follow-up T&E once field use begins in earnest.

If you're building a precision AR in 6mm ARC for hunting, and you're willing to accept a bit more weight for accuracy, this setup is shaping up to be a serious contender.

Coming Soon:

  • Load development results for the 80gr ELD-VT in this 13.9" barrel

  • Gas tuning results with the Odin Works block

  • Final velocity numbers with chrono data

  • Field performance under thermal at night

This post was made July 24, 2025 and will be updated below with field results as they become available.

Part 2: Initial Shooting Results – 6mm ARC Predator Rig – 08/04/2025

With the rifle assembled, optics mounted, and everything torqued and timed properly, I moved into the initial testing phase of this 6mm ARC build. The goal wasn’t just to check functionality — it was to see whether this setup could deliver the precision and consistency needed for nighttime predator hunting out to extended ranges.

Handloads Tested: 80gr ELD-VT and 90gr Sierra TGK

I began load development with two projectiles, each selected with a specific purpose in mind:

  • Hornady 80gr ELD-VT – lightweight, fast, and ideal for predator hunting
  • Sierra 90gr TGK (Tipped GameKing) – a heavier load intended for larger game, such as deer and potentially antelope, should the opportunity arise

While I’m not going to share exact charge weights (I’m not a ballistician, and this isn’t reloading advice), all charges were developed within published safe limits. As always, refer to a reputable manual and work up safely.

Results:

  • 80gr ELD-VT
    • Average velocity: 2830 fps
    • Group size: 1" at 100 yards
    • Notes: Very flat, consistent — looks promising as a primary coyote load
  • 90gr Sierra TGK
    • Average velocity: 2550 fps
    • Group size: 1.25" at 100 yards
    • Notes: Slightly slower, but just as consistent. Wouldn’t hesitate to use this on medium game out to 300 yards

Factory Ammo Results

To establish a baseline, I also ran a few factory offerings through the rifle:

  • Hornady Black 105gr BTHP
    • Average velocity: 2450 fps
    • Accuracy: Acceptable, groups held together decently
  • Hornady Precision Hunter 103gr ELD-X
    • Average velocity: 2379 fps
    • Accuracy: Acceptable for general use, slightly wider than the handloads

Both factory loads were consistent and reliable, though understandably slower through the 13.9" barrel than optimized handloads.

Ballistics & Practical Field Application

80gr Hornady ELD-VT – Flat & Fast

This load is built for speed and minimal drop — perfect for predator work under thermal where fast follow-up and intuitive holds are key.

Zeroed at 100 yards, the trajectory looks like this:

  • 200 yards: 3.09" drop
  • 300 yards: 12.19" drop

Shifting to a 200-yard zero yields:

  • 100 yards: 1.55" high
  • 300 yards: 7.55" low

That creates a very workable holdover zone — I can hold dead-on to ~225 yards, and just hold high at 275–300 yards for a clean hit. With the RIX Leap L3 thermal optic, I can also build a custom reticle with preset stadia for common distances, making this setup extremely field-friendly.

It’s worth noting that I could probably get an even flatter-shooting load with something like the 65gr V-MAX — but I had such great results with the 80gr ELD-VT last year, including no runners, that I’ve chosen to stick with it. I’m also already stocked up on bullets, so this load makes the most sense moving forward.

At 300 yards:

  • Impact velocity: 2215 fps
  • Energy: 870 ft-lbs

Plenty for consistent terminal performance on predators and hogs.

90gr Sierra TGK – Medium Game Precision

For hunting deer and antelope, this load prioritizes retained energy and stability over flatness. My Gen 1 Vortex Viper PST 4-16 is in MRAD, so I built my dope accordingly.

100-yard zero drops:

  • 200 yards: 0.6 mil
  • 300 yards: 1.5 mil
  • 400 yards: 2.6 mil

Retained energy and velocity:

  • 100 yds: 2347 fps / 1101 ft-lbs
  • 200 yds: 2149 fps / 923 ft-lbs
  • 300 yds: 1958 fps / 766 ft-lbs
  • 400 yds: Begins to drop below my preferred ethical threshold

Given the shorter 13.9" barrel, I’m drawing the line at 300 yards for medium game with this load. That still covers the majority of Texas hunting scenarios, especially when paired with a solid tripod or supported position.

Overall Observations

  • Accuracy: 1.5 MOA or better across all tested loads — handloads and factory alike
  • Consistency: No signs of stringing, thermal drift, or POI shift. Everything tracked as expected
  • Recoil & Gas: Odin Works gas block paired with the Sprinco Green spring and A5H1 buffer yielded smooth recoil, clean ejection (~3:30), and no overgassing even suppressed

Next Steps

The rifle is grouping well, running smooth, and showing potential — but paper only tells part of the story. The next phase will be field testing under thermal at night, in real conditions with real targets. I’ll be checking for:

  • Cold-bore consistency
  • Retained zero under varying conditions
  • Whether the 80gr and 90gr loads perform as intended on game

Because that’s what this rifle is for — not benchrest scores, but clean hits in the field, where you don’t get a second chance.