You certainly have your choice of cartridge pairings with AR-style rifles, and even if you stray into the realm of roller-delayed blowback systems such as the MRDS platform developed by Zenith Firearms, you still can take your pick.
As might be expected, 5.56 is well-represented, but there are many other suitable alternatives as well. The 7.62x39mm, also known as the 7.62 Soviet cartridge, comes to mind.
Here are some reasons a 7.62 roller delayed carbine might be a better build than one chambered in 5.56.
Why 7.62 Soviet?
The first draw of the 7.62 Soviet, especially when compared to 5.56, is that it produces considerably more stopping power.
The 5.56, for instance, generally produces between 1200 and 1300 ft-lbs of muzzle energy whereas the 7.62 Soviet generates between 1400 and 1700 ft-lbs.
This makes the 7.62 a harder-hitting round, despite the fact that they are both light, intermediate cartridges. With the 7.62, you get much more stopping power for a compromise on a bit more recoil, but not much.
Which is another thing, because the MRDS platform, being built around a roller-delayed blowback operating system, helps to absorb recoil, resulting in a much smoother-shooting platform, even with the heavier cartridge.
In addition, the roller-delayed blowback system of the MRDS platform responds well to suppression, which is another draw, though it is not specific to 7.62 Soviet.
Back to the cartridge in question; it also performs fairly well from a shorter barrel, so for those of you looking at your options in terms of SBRs or carbines, the 7.62 generally performs better from these than 5.56 does.
Not that 5.56 performs poorly, but short barrels don’t give the propellant charge time to fully deflagrate. The slower-velocity 7.62 Soviet doesn’t need as much barrel length as 5.56 does.
On top of the fact that 7.62 generates more muzzle velocity and thereby stopping power than the 5.56, and performs better from a shorter barrel, it is still a very affordable cartridge and widely available.
This makes it ideal for builds that are used not just for high-volume shooting disciplines, but also for sporting and defensive applications. Loaded with an appropriate bullet it can be even more effective for these than 5.56.
There is one big tradeoff with 7.62, though, and it is the range. It does not perform well at extended ranges. You could push it past 100 yards, but realistically, the trajectory starts to drop off pretty badly after that point.
Where to Learn More About the MRDS Platform?
Thinking a 7.62 roller-delayed carbine is for you? It might be, but if you want to learn more about the MRDS platform before you buy, check it out online at Zenith Firearms. You can learn more on their website or get in touch with them directly at Info@ZenithFirearms.com; they’d be happy to assist or answer your questions before you order.
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