Hog Hunting 338 ARC: Safer, Better, And More Fun [BUILD]

When it comes to Hornady, two things are inevitable: introducing new cartridges, and people hating on Hornady's new cartridge. Americans born the same year that 6.5 Creedmoor was introduced are old enough to vote this year, but that doesn't stop people from hating on it 18 years later.

When Hornady introduced the 338ARC to the public last year, it was immediately met with hate and derision from a few corners of the internet, as well as one outspoken industry ‘personality' that likely saw it as a threat to one of his pet projects. 

Now, 12 months later, how does the newest, fattest member of the ARC family stack up?

Spoiler – it's actually pretty awesome. 

338ARC caught my attention as soon as it was announced. I'd always liked the idea of 300 Blackout for giving solid subsonic performance from a semi-auto rifle, with better ballistics than a pistol cartridge, but I could never quite accept the risk of seeing it get mixed up with 5.56 ammo on the range. 

I work with a lot of new shooters, and the idea of being the latest person posting pictures on the internet of their destroyed rifle after a mishap always gave me the willies. Thankfully, 338ARC resolves that problem, and that situation is also moot with its 6mm and 22-caliber brethren. As a bonus, the 338ARC is able to sling heavier bullets with higher BCs than the 300 Blackout, with the potential for more energy on target and less drop at moderate distances. 

To get some hands on time with the 338ARC while waiting on an announced but yet-to-be-released complete firearm to be available, I decided to build up a new upper for my existing AR-15 SBR lower to see if it could live up to the promises and hype, or alternatively see if the hate was deserved. 

Here's the build specs on the upper:

• Faxon 338ARC-specific upper receiver
• Faxon 338ARC 11.5″ barrel, 1/5 twist
• Faxon adjustable gas block
• Seekins Precision MCSRV2 15″ handguard
• Faxon Harmonix Ion 36 suppressor, Area 419 Hellfire mounting system
• Faxon ARC bolt in a Seekins bolt carrier
• PRI Gas Buster charging handle
• SIG Romeo 5 Gen 2 Elite red dot with 1.93″ I-Beam mount

The lower receiver was unchanged from its usual configuration for my 10.5″ suppressed 5.56 upper, including an H2 buffer, standard carbine spring, and Geissele SD-E trigger. 

Testing was done with 175gr supersonic and 300gr subsonic AAC ammo I picked up from Palmetto State Armory on a recent trip through South Carolina, 307gr Hornady Sub-X I purchased from one of my usual go-to online vendors, as well as a healthy amount of my own handloads using AAC brass, Accurate brand powder, and Lapua bullets.

THE MAGAZINE-SHAPED ELEPHANT IN THE ROOM

Thanks to having several 22ARC ARs in the safe already, I have also been able to test a variety of magazines – 10, 15, 20, and 26 round mags from DuraMag, as well as 25-round AR-Stoner branded magazines. Keep in mind that none of the tested magazines are listed as 338ARC magazines, and most suggestions online are to use 400 Legend or 338ARC specific magazines for the cartridge. 

Based on much of the commentary I had seen online regarding magazines, I started off with 10 and 15rd DuraMag magazines, but loading them short of their full capacity – 5 to 8 rounds in the 10s and 10 to 12 rounds in the 15s. I also tried roughly 15 rounds in a 20 round magazine. Despite the cautions I'd seen online, and much to my pleasant surprise, all of the mags ran flawlessly with 300gr AAC ammo. 

After probably 40 rounds of this, I decided to go for broke, and started jamming magazines to their full capacity. Total malfunctions with 15, 20, and later 25 round DuraMags on my first range trip?

Zero malfunctions in 250+ rounds. None. That was with roughly 200 rounds of 300gr AAC subsonic, 40 rounds of 175gr supersonic, and 20 rounds of Hornady SubX. 

From there, I worked up a subsonic load with some 250gr Lapua Scenars I had laying around from another project, and found a happy load running those at 1080fps. Over 200 rounds of that later, plus some additional 300gr AAC mixed in and with magazines always loaded to capacity, I was still running almost flawlessly. 

In nearly 500 rounds fired I had two or three occasions where the first round didn't strip off the top of a fully loaded magazine, and it only happened when I used the bolt release instead of the charging handle. In each case, the malfunction was rectified with a quick stroke of the charging handle, and I was back up and running. At no point with my DuraMag testing did I have a malfunction outside of those incidents. 

It's also worth noting that the carbine spring in this lower has seen a lot of cycles with my usual suppressed 5.56 upper, so I can't even conclusively say that the issue was the mags and not a slightly weakened recoil spring. Color me impressed.

Towards the end of my testing process, I acquired the previously mentioned AR Stoner brand 25rd magazines. I actually got these for one of my 22ARC builds, but figured that they'd be worth testing in the 338ARC upper. They have significantly less curve than the DuraMag branded 25rd mags, and the reinforcing rib is in a somewhat different location and much deeper, so I was curious to see how they'd run. 

Unfortunately, these magazines were far from flawless with my hand loads. After 75 rounds with roughly 10 stoppages, I put them back in the bag with my 22ARC gear. 

While my magazine testing wasn't without issue, my experience with this build and the DuraMag left me with a much less downcast outlook for 338ARC than many of the online pundits would have you believe. I think some of the credit here belongs to Faxon, as their uppers and barrels are cut with very generous feed ramps to aid in reliability. 

VELOCITY TESTING

One of the stated benefits of the 338ARC case design is much more consistent subsonic performance than some of the competing designs. With that in mind, I ran 10 rounds each of the AAC 300gr subsonic and 175gr supersonic loads in front of my Garmin Xero chrono, as well as 10 rounds of the Hornady 307gr SubX. I found the following results:

While this is only a random 10-round sample of each of the ammo offerings, those numbers are very good for factory ammo. It can be especially tricky to get subsonic loads with that kind of consistency. I also didn't notice any real signs of unburned power, fillers, etc even after several hundred rounds of testing, so I think there's some credit to be given to Hornady on the case design as well as Hornady and AAC on their ammo. 

After some load development work, I was able to load up some Lapua 250gr Scenars over Accurate 5744 powder in AAC brass for the following results over 11 shots:

250gr subsonic hand loads:

• Average – 1077.5FPS
• Standard Deviation – 6.0fps
• Extreme Spread – 20.3 FPS

I'll take that.

In the midst of all of this, I was also paying a lot of attention to sound levels with 338ARC subsonic and the Faxon suppressor. They sounded excellent, and several friends I let try out the 338ARC upper commented on how quiet the whole thing was. The Faxon suppressor also ensured there was absolutely zero gas in your face, which frankly wasn't a surprise given what I'd already seen with it on much gassier hosts. Keep an eye out for the full review on the Harmonix coming in the future. 

I was also able to use the BDC reticle option in the SIG Romeo 5 Gen II Elite (man, that model name's a mouthful…) to stretch my 250gr subsonic loads out to a little more distance. With an 18 yard zero to maximize point blank range for possible hog hunting, the BDC dots and 65 MOA circle gave me holdover points for approximately 155, 180, 225, and 325 yards respectively. Even at 300 and 350 yards, the steel at my local range rang quite clearly and gratifyingly from those 250s thumping into them. 

Unfortunately, I haven't had a chance to source some 300gr match bullets yet, but I plan to do so in the future and see how they perform when driven to the same ~1075fps speeds I loaded the 250s at. It's worth noting that 5744 let me ramp the speed up to almost 1500fps without pressure signs on those 250s, so there was a lot of performance left to squeeze in exchange for getting a supersonic crack with each shot. A 300gr bullet at 1075 should be quite impressive, though, as well as extend the reach a little further without having to go to a LPVO with a deeper reticle. 

THE ARC FAMILY'S ACE IN THE HOLE?

There's one trick that remains to be fully seen with the 338ARC, and it's one that will benefit the entire ARC family – Magpul's ICAR magazine. It's very similar to the Six8 pattern magazine they produce for LWRC's Six8 receivers, which were originally designed for the 6.8SPCII cartridge that has faded into near obscurity in the last few years. The new ICAR format, which is named for a Surefire DoD contract for a 6ARC assault rifle, is being picked up by more manufacturers with the promise of rifles and receiver sets being in the commercial market in the near future. 

So, what's the big deal? Simply put, the magazine is wider, allowing for proper stacking of rounds in the magazine and much more reliable feeding. It also allows for proper curvature of the magazine without potential binding issues that come with a mismatch in the case taper compared to 5.56.

To accommodate this, the magazine well on the lower receiver must be cut to fit the wider magazine, and the upper receiver must also leave room for the wider feed lips. However, you're still getting functionally an AR-15 sized receiver set with much smaller and lighter weight than an AR-10 sized rifle, and the larger upper also opens up the potential for a fatter, stronger bolt. That stronger bolt will really be a benefit in the 6 and 22ARC cartridges, and potentially allow them to be run at bolt gun chamber pressures from a semi-auto with a matching gain in muzzle velocity. The ICAR magazine still holds potentially huge benefits for the 338ARC, with the promise of a 25 round magazine that runs just as reliably as a 30 round 5.56 PMAG does with a 5.56 AR, even when packed with 300gr subsonic ammo.

Palmetto State Armory is arguably the highest profile company to already announce new ICAR-pattern firearms and receivers, with a 338ARC and ICAR variant of their Mixtape pistol coming in the near future. I fully expect they will be joined by quite a few others, especially as the 6ARC picks up more momentum from civilian shooters and military contracts. 

LOOSE ROUNDS

My journey into 338ARC has been a rewarding one. While magazines can be a twitchy issue with the new cartridge, my experience has shown there is a short term path to reliability, especially for recreational shooters. 

I'm personally hopeful we will see more ammo and projectile options over the coming months and years, such as Hornady's 307gr SubX bullet being available as a component, some 300gr bonded soft point options for hunting and possibly specialty law enforcement uses, and maybe even some cheaper plated bullet options for plinking steel and paper at the range. Magpul's ICAR magazine also holds promise for really making 338ARC a subsonic powerhouse. 

Overall, I'd say Hornady is delivering on their promises for the 338ARC, and I am very interested to see what the future holds for it.

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