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Can You Shoot 10 MM Out of a .40? | Read Before Trying

You can likely shoot 10 mm out of a .40, but it is not recommended. The 10 mm round is a bit longer than the .40 S&W, so it will not fit in the chamber correctly. The 10 mm also has more powder and creates more pressure, so shooting it out of a .40 caliber gun could be dangerous.

Stick around as I explain exactly what would happen if you were to shoot a 10 mm round out of a .40 caliber gun.

Handgun next to 10mm rounds

The Difference Between the 10mm and .40 S&W Rounds

The main difference between the 10 mm and .40 S&W rounds is the size. The 10 mm is a longer bullet, measuring .142 in (3.6 mm) more than the .40 S&W round.

This size difference means the 10 mm has more powder and creates more pressure. This can be dangerous because the .40 caliber gun is not designed to handle that much pressure. The 10 mm round will also not fit in the .40 caliber chamber properly.

When you try to shoot a round that is the wrong size for the firearm, the gun usually jams. A 10 mm round might fit far enough into the chamber to fire but this is dangerous because the pressure could cause an explosion.

Will a .40 Gun Fire 10 mm Rounds Reliably?

The simple answer is yes, a .40 S&W will fire 10 mm rounds. In fact, people use them for hog hunting all the time. The problem is that .40 cal firearms are not created equal. Some will shoot 10 mm rounds reliably, while others won’t. 

Here are some potential problems of firing 10 mm rounds in a .40 cal gun:

  • You risk malfunction.
  • The gun may not extract the spent casing properly.
  • You may have increased wear and tear.

So, while you can shoot 10 mm out of a .40, it’s not recommended. The 10 mm round is just too long for the .40 S&W chamber and can cause problems.

Montage of 10mm rounds next to two handguns

Should You Use 10 mm Rounds With a .40?

If you’re still undecided about whether or not to shoot a 10 mm out of a .40, there are a few things you need to consider. First, think about why you want to do it:

  • Are you trying to save money on ammo? The 10 mm round is more expensive than the .40 S&W, so you’re not going to save any money by shooting it in a .40 caliber gun.
  • Are you trying to increase the power of your .40 caliber gun? The 10 mm round is more powerful than the .40 S&W, but it’s longer and can cause problems in a .40 caliber gun. It’s not worth the risk of damaging yourself or your gun.
  • Are you trying to shoot a 10 mm round because you can’t find .40 ammo? If you can’t find .40 ammo, you’re better off buying a 9 mm. The 9 mm is cheaper and easier to find and will work just as well in a self-defense situation.

So, if you’re still undecided about whether or not to shoot a 10 mm out of a .40, ask yourself why you want to do it. If you can’t come up with a good reason, you’re probably better off not doing it.

How To Stay Safe When Shooting 10 mm Out of a .40 Cal Gun

If you’ve made up your mind, and you’re going to shoot a 10 mm out of your .40 gun, here’s everything you need to know:

  • Make sure your gun is in good condition: Using a damaged gun is always a dangerous gamble. This is especially true if you’re going to be shooting a round longer than the one it was designed for. That’s why it is important to inspect your gun for cracks or damage in the barrel or chamber.
  • Keep an eye on the degradation: Shooting a 10 mm out of a .40 gun will cause more wear and tear on the weapon than shooting a .40 S&W. If you notice any unusual wear or damage, stop using it and have it inspected by a qualified gunsmith.
  • Be prepared for malfunctions: Shooting a 10 mm out of a .40 gun is more likely to cause a malfunction than shooting a .40 S&W. Be prepared for this and know how to clear a jam if one occurs.

Final Thoughts

People have shot 10 mm out of .40 caliber guns for years, but it’s recommended. The 10 mm round is longer than the .40 S&W, and it can cause problems in the gun, including increased wear and tear, jams, and malfunctions.

If you’re still undecided about whether or not to shoot a 10 mm out of a .40, ask yourself why you want to do it. If you can’t come up with a good reason, you’re probably better off sticking to the correct round for the gun at hand.

For more, check out Gun Show Ammo Prices | Will You Save Money?

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