Engineering Suppression: Can a 7.62x51 Round Sound as Quiet as a 22 LR?

Have you ever wondered if with enough engineering, it could be possible to make a 7.62x51 round sound like a 22 LR round being fired from a gun? While some may think a 7.62 suppressor like the Rugged Radiant could do the trick, the reality is more complicated.

Short Answer: No

The short answer is no, but let's delve into why.

Long Answer: Complicated Engineering

The energy and efficiency of a 7.62x51 round are crucial factors in sound suppression. A 147-180 grain bullet moving at between 2600 and 2800 fps generates significant energy, which diminishes substantially when the velocity is significantly reduced, typically by more than half, resulting in roughly 1000 fps. Although increasing the mass of the bullet can help, the limitations are significant, making the task of achieving the quietness of a 22 LR round challenging.

Suppressor Technology and Subsonic Ammunition

The problem goes beyond just suppressor technology. The sonic crack, the sound made when the projectile breaks the sound barrier, is why subsonic ammunition is preferred. This is a substantial hurdle in sound suppression because the dynamics of launching subsonic projectiles are vastly different from those of supersonic ones. Additionally, subsonic projectiles require a more efficient suppressor to manage the gas and pressure effectively.

Designing for Suppressed Use

For practical reasons, it's often more practical to design a new platform specifically for suppressed use rather than trying to adapt an existing rifle to suppression. This is illustrated by the existence of dedicated suppressed platforms like the .300 Blackout (300 BO) and the .860 Blackout (8.6 BO).

Optimizing for Suppression

Starting with a lighter rifle is a logical choice. Rifles like the .308 Winchester, .30-06 Springfield, or .300 Win Mag are heavy and bulkier than necessary for a suppressed platform. The dynamics of launching heavy subsonic projectiles are fundamentally different from those of supersonic ones due to stability concerns. The 8.6 BO, for example, uses a 1:3 twist rate, which is over three times that of a standard .308 Winchester and more than twice that of the 5.56 NATO. This difference is significant, making it akin to comparing apples to hobnails.

Potential for Engineering

While a 7.62x51 round can theoretically be made quieter with enough engineering, the practical limitations are substantial. As long as the projectile is subsonic, the challenge lies in designing a suppressor that can sufficiently slow down the gases coming out of the muzzle. A heavier projectile would require a bulkier suppressor due to the increased pressure needed to expel it at around 1000 fps.

Practical Quieting

A rifle chambered for a 147 grain 7.62x51 round could indeed be made quieter than a 7.62x51 with a standard suppressor. However, making a hypersonic 7.62x51 projectile quieter than a hypersonic 22 LR is practically impossible, given the inherent dynamics of supersonic and subsonic projectiles.

In conclusion, while it is possible to make a 7.62x51 round sound like a 22 LR with enough engineering and the right platform, the practical and engineering challenges are significant. The design and optimization particularly for subsonic projectiles play a crucial role in achieving this goal.