I saw this video on YouTube and thought it was worth sharing. As some of you may know, I like slow motion especially when it pertains to firearms. Well, the Slow Mo Guys have access to some of the best slow-motion cameras and have occasional videos using firearms in slow motion. This time they used a pinfire pistol to shoot the back of a 9mm and .22LR cartridge. The results were surprising.

Slow Motion @ TFB:

• Shooting a S&W Model 61 in Slow Motion
• DIY Schlieren Imaging of Bullets In Slow Motion
• Slow Mo Guys 1 Million FPS – 9mm vs Egg and Newton’s Cradle

Here is the video:

Now let’s break down what happened.

They clamped the pinfire pistol in a vise and glued the 9mm cartridge to another vise. They used a piece of string to remotely fire the pinfire pistol. As the pinfire pistol hammer falls, you can see a flash. One of the shots they captured had a sort of hang fire. The one I screen capped below did not.

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Credit: Slow Mo Guys

After some muzzle flash, the ball projectile leaves as seen below. It hits the primer on the back of the 9mm case. This ignited the primer and due to the burning gasses in the 9mm cartridge, it sends the primer rocketing backwards into the barrel of the pinfire pistol.

Credit: SlowMo Guys

Credit: Slow Mo GuysThe primer flew back because there was no breech to support the case and primer. Even with a barrel, I think the primer would be blown out the back. The primer ignited and managed to cause some of the gun power to flow out the back.

Credit: Slow Mo Guys

But there was a lull and more gun power flew out with vigor. Possibly a hang fire where the heat inside cooked some of the gun powder and it took the path of least resistance and flowed out the back.

Credit: Slow Mo Guys

For one of the shots, they did manage to get bullet separation from the casing.

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Next, they shot a .22LR cartridge with the pinfire pistol.

Since the rimfire cartridge does not have a removable primer, the case acted like a small rocket and flew back with gusto into the barrel of the pinfire pistol.

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Credit: Slow Mo Guys

Then they used a probe macro lens to really see the back of the rimfire cartridge.

Credit: SlowMo Guys

I was truly surprised to see how much deformation the pinfire ball caused to the back of the cartridge.

Credit: SlowMo Guys

Then I was blown away by the mushrooming effect of the powder pushing the cartridge case back out like a dome before it rocketed away.

Credit: Slow Mo Guys

Credit: Slow Mo Guys

The Slow Mo Guys have some very interesting content and I am glad they are willing to look at firearms with their cameras. Check out their YouTube page for more videos.