Can you build a 5.56 rifle with a side-charging AR upper? Absolutely. Should you? That depends on what you’re looking for in a rifle.
Sure, 5.56 is widely available, every gun shop has it, and it’s cheap. It produces little recoil, shoots flat, and has a wide range of sporting applications.
But in terms of ballistic performance? There are a lot of other calibers that hit harder and offer other advantages. Let’s take a closer look at some of these.
.308 Winchester
If you’re looking at an AR build and you want more power and performance from a “common” rifle cartridge, this is one of the best ways to go.
Relatively similar in performance to the 7.62 NATO cartridge (which was the predecessor of the 5.56) .308 Winchester is one of the best “all-around” rifle cartridges in the country.
Yes, it is more expensive than 5.56 and kicks harder, but it produces considerably more recoil and can be used for sporting applications, effectively on any game in North America. On top of that, it’s not a terrible long-range shooter, either, even though it drops faster.
.300 BLK
We won’t mince words. The .300 BLK is an expensive cartridge and not every shop carries it. But it offers two serious advantages over 5.56: power and performance from short barrels.
For one, .300 BLK offers considerably higher stopping power, especially at close ranges, than 5.56. It also performs very well in very short barrels, even SBRs with sub-16” barrels. Also, it performs well from suppressed platforms, too.
On top of that, you can use a lot of the same parts (obviously not the barrel) for a 5.56 build and a .300 BLK build, which is another selling point. And, if you reload, you can keep old 5.56 brass, neck it out, and reload it as .300 BLK.
The one big drawback is that .300 BLK drops like a rock, so keep it for close and intermediate engagements.
.338 ARC
The .338 ARC is a close-range hard-hitter that’s optimized for performance through suppressed builds.
It has a small case capacity and a heavy bullet, so it performs well from short barrels, shoots like a whisper when suppressed, but hits pretty hard.
The one thing is that this is a heavy bullet, so you’ll want a fast twist rate in the barrel you choose for the build, something like 1:5.
6mm ARC
The 6mm ARC is all about pushing a 6mm bullet fast, and keeping it fast and lethal even at great ranges. A 6mm ARC round can stay above 1800 FPS almost to 600 yards, and will stay supersonic past 1000.
It’s a niche cartridge, and only Hornady loads it, but if you’re looking for a 5.56 alternative that hits harder at considerably greater ranges, this might be it.
6.5 Creedmoor
Extremely accurate, even to and past 1000 yards, and hard-hitting, the 6.5 Creedmoor has been effectively dubbed a “magic bullet” by big game hunters around the world.
If what you want is power at considerable ranges, without punishing recoil, then 6.5 Creedmoor is an excellent option for a side-charging AR upper.
Where to Get Side-Charging AR Uppers in These Calibers?
Interested in a side-charging AR upper in one of the chamberings, or some other alternative to 5.56? The first place you should check out is Gibbz Arms.
They produce the highest-quality, precision-manufactured side-charging AR uppers and builds in the industry, and have partnered with Mos-Tek to include barrels in their builds with optimal matching and twist rate to generate maximal accuracy and range from some of these niche cartridges.
Stop there first and get in touch with them if you have any questions.
For more information about lefty ejection port and Upper Charge Please visit: Gibbz Arms.
