The U.S. Marine Corps has been using the Mk 153 Shoulder-Launched Multipurpose Assault Weapon (SMAW) since it was introduced in 1984, but don’t feel bad if you aren’t familiar with it. It doesn’t get a lot of press, would likely never be seen outside a war zone, and hasn’t really been featured on screen, other than a couple brief scenes in Kick-Ass (2010) and The A-Team (2010) (neither of which showed of its distinctive feature).

First, take a look at how the rifle part of the weapon system runs in the video above and let’s talk about a similar weapon system constructed in a similar way.

For most of the Vietnam War, a grenadier was issued the single-shot break action M79 grenade launcher and not much more than an M1911A1 .45 ACP pistol for any close encounters, of which there were many.

A soldier holding a M79 break-action 40mm grenade launcher in Vietnam.
A soldier holding a M79 break-action 40mm grenade launcher in Vietnam. photo from

Since grenades, especially those fired from a launcher, are used for very specific purposes in a limited set of circumstances, it was soon realized that having a grenade launcher as a primary weapon was not ideal.

In 1969, the M203 began to phase out the M79. It was also a single-shot launcher that fired the same 40mm rounds as the older M79, but the big difference was that it was designed to be attached under the barrel of the M16 rifle and later the M4 carbine.

The reality is, 40mm grenade ammo is heavy and bulky, limiting the quantities that can be carried. With the M203, when a grenadier is on patrol, he can serve as a fully capable rifleman, until a grenade is needed. Then he can easily switch to the launcher by using the magazine as a handle to fire the launcher trigger located just in front of the magazine well. It also allowed grenadiers to better defend themselves on the battlefield between firing grenades.

The M320, a similarly designed grenade launcher, will eventually replace the M203 in the U.S. Army, while the other branches of the service still rely on the M203.

An M4A2 with an M203 40mm grenade launcher attached.
An M4A2 with an M203 40mm grenade launcher attached. photo from wikipedia

The SMAW was designed with similar logic, but for a vastly different purpose. It’s basically a rocket tube with a rifle attached to the side of it. In the video above it looks extremely awkward to fire, until you realize the purpose of the “rifle.”

It’s actually a semi-automatic spotting rifle that fires the 9x51mm Mk 217 spotting round, which is ballistically matched to the rocket in the tube. The cartridges contain a tracer compound, crimped into a 7.62x51mm NATO casing with a .22 Hornet primer.

That’s what the troops in the video are firing at the target (more likely it’s the Mod 2 variant with an electronic modular ballistic sight). The tracer rounds help increase the first-round hit probability of the rocket launcher by essentially tracing a path for it and the shooter before the rocket is fired.

The SMAW firing a training rocket.
The SMAW firing a training rocket. photo from wikipedia

The launcher tube can fire four types of rockets: the Mk 4 Mod 0 Encased High-Explosive, Anti-Armor, Practice Rocket for training purposes; the Mk3 Mod 0 Encased High-Explosive, Dual-Purpose Rocket, which is effective against bunkers, masonry, and concrete walls as well as light armor; the Mk 6 Mod 0 Encased High-Explosive, Anti-Armor Rocket, which is effective against current tanks and works like a shape charge; and the Mk80 Mod 0 Encased Novel Explosive Rocket, which is effective against caves and bunkers and uses a thermobaric warhead that produces an overpressure wave that can collapse a lightly constructed building.

It’s a very specialized weapon system, but at the same time it’s extremely versatile, and it’s basically a rifle and a rocket launcher mashed together—so that’s just cool by default.

Read more about the SMAW here.