Thinking about building an AR-15 side charger? Don’t just build another rifle in 5.56 if you already have one (or several) in the safe, even if this one will be a side charger.
There are many other cartridges out there, each of which offers unique and relative attributes. One of them is a very young cartridge only recently developed by Hornady; the 6mm ARC. Don’t just settle for what’s easy; let’s take a closer look at what this cartridge can do, which as you will find, is most of what smaller calibers can, and a lot of what larger calibers can.
The Advances – and Limitations – of 6mm ARC
First, let’s cover what the 6mm ARC actually is. Also known as the 6x38mm or 6mm Advanced Rifle Cartridge, the 6mm ARC is a .243 caliber, intermediate rifle cartridge developed by Hornady in 2020.
If you look at it next to a 5.56 cartridge, you will see that it has a larger, wider case, a sharper bottleneck, and a considerably longer, heavier bullet – despite the fact that overall length (OAL) is very comparable.
The parent cases were the .220 Russian and 6.5mm Grendel, from which it took some of its inspiration as the latter is a somewhat popular and heard-of AR cartridge.
Depending on load data, the 6mm ARC can generate muzzle velocities as high as 2800 FPS with muzzle energies in the area of 1760 to 1814 ft-lbs. All in all, this cartridge was developed to be a highly accurate, blazing fast long-range cartridge that produced relatively little recoil.
Although it also performs well in bolt action platforms with longer barrels, the 6mm ARC was developed to achieve new performance in the AR-15 platform. With an assortment of bullets, it delivers excellent terminal performance that’s well-suited to a wide variety of shooting disciplines, including but not limited to long-range competition and sporting applications such as hunting.
One defining characteristic of the 6mm ARC is that, despite the similar OAL to the 5.56x45mm NATO cartridge, the 6mm ARC has a much shorter case and longer bullet. The takeaway here is that longer, thinner, heavier bullets tend to have high ballistic coefficients but still carry a lot of energy downrange.
In other words, they shoot flat but still hit hard when they get there, unlike the 5.56, which shoots flat, but loses energy relatively quickly because of its lower mass and correspondingly lower sectional density.
In addition to long-range shooting, which is one of the most fitting applications of the 6mm ARC, it is also suitable for hunting medium and large game such as mountain lions and black bears. It’s more than powerful enough to dispatch whitetails, too, even at several hundred yards – and we all know how divisive .223 and 5.56 are for deer hunting. Some states won’t even allow it.
Of course, there are other larger cartridges that are suitable for dispatching medium and large game – .30-06 comes to mind – but cartridges like these are generally not compatible with the AR platform, whereas the 6mm ARC is.
This is arguably the greatest selling point of the 6mm ARC. If you want to have your sporting rifle and use it for long-range hunting, too, the 6mm ARC is perfect for that. Lighter alternatives (like .224 Valkyrie or 5.56) are too light or too unstable at greater ranges, and on the other end of the spectrum (such as in the case of the parent, 6.5 Grendel) they can’t compete. The 6mm ARC carries more energy, for longer, and is just as accurate if not more so.
And now, thanks to our unflinching efforts, you can build an AR-15 side charger around this cartridge.
Superiority in AR-15 Side Chargers
Everything about our AR-15 side chargers chambered in 6mm ARC is engineered not just to perform, but to excel.
We paired our non-reciprocating side charger with a gas trap system that is suppressor friendly (another advantage), reducing recoil and enhancing the smooth cycling of the action.
Lower recoil and reduced muzzle flip together keep you trained on target so you can make faster, more confident, and most importantly, more accurate follow up shots.
We also paired these components with a Mos-Tek match-grade barrel with headspace-matched bolt carrier groups that deliver a better, surer lockup and greater handling, cycling, and overall performance.
(That said, this AR-15 side charger is also compatible with all mil-spec bolt carrier groups, if you want to swap the stock BCG out.)
The Mos-Tek match-grade barrel is made of 416 stainless steel with a pinned gas block and sports a 1:7 twist rate which has been proven ideal for these heavy, skinny bullets, ensuring optimal stability even at extended ranges, for pinpoint precision whether your target is paper or your intended harvest.
This AR-15 side charger is also compatible with standard capacity AR-15 mags, sports a flared magwell, and comes with a full-length Pic rail for mounting shooting accessories like optics. For you long-range shooters, the side-charger configuration is superior for this cartridge because it gives you the flexibility to mount oversized optics so you can take advantage of the extended performance of the 6mm ARC cartridge.
All in all, this side charger is optimized for unparalleled accuracy, especially with the 6mm ARC, as well as for durability, shooter-friendliness, suppression, and expandability.
For more information on this AR-15 side charger platform, contact us or see our G4 6mm ARC page.
Explore AR-15 Side Chargers and Parts
Two things are clear: the 6mm ARC, though a niche, and specialized, cartridge, offers considerable relative advantages over others that are more commonly paired with the AR platform. The other is that a side-charger gives you greater flexibility with mounting optics – among others, such as that you can manipulate the action without breaking your cheek weld.
Shop our collection of AR-15 side chargers and parts and if you have any questions get in touch with us directly for more information.