While many, perhaps even most, ARs and AR-style platforms, including ARPs, are chambered in 5.56, the modern market has a lot more to offer you.
From .300 BLK, which will enable you to use many of the same parts as a 5.56 build, to big behemoths like .50 Beowulf, you don’t need to settle for 5.56.
Yet you also don’t need to go with something newer, as in the last two alternative cartridges involved. You might even choose to go with something older even than 5.56, like 7.62 Soviet.
On that note, here are 4 of the best reasons to choose a 7.62x39 upper for your next build over 5.56, whether you intend to build an ARP or a full-size rifle.
Stopping Power
The first and most significant advantage that 7.62x39mm has over 5.56x45mm NATO is that of power. Also known as 7.62 Soviet to distinguish it from 7.62 NATO, which is a newer cartridge, the former delivers considerably more stopping power, especially at closer ranges, than 5.56.
The 7.62x39mm fires a larger, heavier, 7mm-class bullet, whereas the 5.56 fires a 5mm-class bullet. Though it produces lower muzzle velocities, it also produces muzzle energy that is much higher.
There is a great deal of variety in load data that makes averages a little hard to visualize, but to keep things as simple and straightforward as possible, you can expect muzzle energies in the area of 1150 to 1300 ft-lbs for 5.56, whereas 7.62 Soviet produces muzzle energies generally between 1400 to 1700, which is much higher.
Even taking energy aside, the fact that the 7.62 Soviet is loaded with a larger, heavier bullet also means that it produces a wider permanent wound channel and that, on top of that, it offers better penetration at closer ranges.
This makes 7.62 Soviet preferable for defensive applications when loaded with an appropriate bullet, and also gives it better stopping power when it is used for sporting applications, such as hunting or for predator or varmint control, at both of which it excels.
But stopping power is only the tip of the spear here. A 7.62x39 upper will also give you more flexibility with regard to the size of the platform you build.
Better Performance from a Short Barrel
The 5.56 really benefits from a longer barrel which gives the propellant time more charge to deflagrate and the bullet more time to accelerate before it leaves the bore. It is a fast, flat-shooting cartridge, which is its main benefit.
This is not the case for a 7.62x39 upper, or for the 7.62 Soviet cartridge in general, which is neither particularly fast nor a flat-shooter. What it does is hit hard up close.
As a result, a longer barrel is not really necessary for the 7.62 Soviet to deliver the performance desired. This it shares in common with relatively similar cartridges like .300 Blackout, which also perform well from an upper with a shorter barrel.
If you chamber in 5.56 and build an SBR or an ARP, you will likely deal with a lot of muzzle pop and extra fouling, not to mention the loss of some of what 5.56 could offer you from a longer barrel.
With a shorter barrel and a 7.62 Soviet chambering, you’ll get just about the same performance you’d get from a longer barrel.
As a result, it makes more sense to chamber an ARP or SBR in 7.62 Soviet, especially if what you’re looking for is a platform that handles well in tight quarters and offers better performance than 5.56.
Ammo Availability
While 7.62 Soviet is not as ubiquitous or as cheap as it used to be, it is still a very widely available and highly affordable ammo, all things considered.
It is generally more affordable than other similar cartridges that offer somewhat comparable performance, like .300 BLK, making it a suitable alternative. The relatively low cost makes it an effect cartridge for range training, too, just like 5.56.
Plus, it won’t produce too much more recoil than 5.56, making it a relatively light shooter as far as rifle chamberings are concerned.
It’s Something New
Lastly, if you have several sporting platforms already chambered in 5.56, the 7.62 Soviet is a new cartridge for you to experiment with, especially given all of its use cases from defensive to sporting applications.
Shop 7.62x39 Uppers Here
Looking for a 7.62x39 upper for your next build? Check out our collection of assembled uppers and if you have questions about the build, or about the compatibility of parts, get in touch with us and we will be more than happy to assist.