It took me about a minute into Wally’s excellent article to figure out I didn’t know near as much about Recoilless Rifles as I thought I did, and nothing about this one. My experience with these weapons was the 75mm and 106mm versions that were mounted on the M-38 Jeeps or the M274 Mechanical Mules. The early roots of the weapon I knew nothing about.
The M18 was developed by Firestone Tire and Rubber of all unlikely sources, and was the first recoilless rifle system to see volume production. They entered service in 1945, reaching the battle fields near the end of World War Two. The object was to develop man portable artillery to deal with tanks and other hard targets.
At forty five plus pounds this was something of a stretch, but do-able. The ammunition was also heavy, five pounds a round. The length of the beast, combined with the weight made it acquired carry. The M18 was intended to be shoulder fired, as seen in this photo. This could be done, but the squads soon decided the tripod was worth the extra blood, sweat and tears. The thing is, the M18 could throw a two and a half pound projectile a mile with a good deal of accuracy. It was worth it!
Now lots of folks (like me) have been confused as to how a recoilless rifle works. I mean – what’s with all the holes in the casings. I know there are lots of GI’s out there with this bar that are laughing their heads off, but bear with me. I doubt I’m the only person on the net that didn’t know this stuff.
Unlike most firearms, the chamber of a recoilless rifle isn’t a tight fit around the case below the neck. A plastic or paper sleeve is set inside the case to hold the powder in place. When fired the gas blows through the sleeve and expands into the bell and pushes the projectile down range.
This chart shows the venting out the back to counter the thrust of the projectile. That is both why there is no kick (to speak of) and the reason you don’t want anybody who owes you any money standing behind it! All kidding aside, the back blast is deadly AT LEAST 100 feet back. From what I’ve heard you can hear one of these go off in the next county.
So, can these be fired? Yes and no. Casings and projectiles for these weapons are hard to find and expensive when you do. But if you’re looking to reload the original ammo you won’t be worried about the price. These are considered destructive devices. If I recall correctly, the tax on those is five thousand dollars.
Then again, Uncle Sam was worried about the cost of training thousands of soldiers and marines, so they developed a “sub-caliber training device”. And what is that you might ask? The most common were .30-06 barrels that could be fitted inside the weapon. That’s the way most folks fire them today.
As much fun as I could have with the 57mm, I think it would be a ball to try out one of the sub-caliber versions one of these days.