Shooting The Wrong Ammo In A 308

Published on December 19, 2025
Duration: 15:58

This video demonstrates the dangerous consequences of firing incorrect ammunition in a .308 Winchester rifle. The host, exhibiting high-level expertise, tests .243 Winchester, .260 Remington, and 7mm-08 Remington rounds, highlighting issues like fire-forming brass, extreme inaccuracy, tumbling projectiles, and significantly reduced velocity due to gas blow-by. While technically possible in a dire emergency, the experiment concludes that using the wrong caliber is ineffective and hazardous.

Quick Summary

Firing incorrect ammunition, like .243 Win in a .308 rifle, is dangerous and ineffective. The undersized bullet causes gas blow-by, drastically reducing velocity and causing tumbling, leading to keyholing and severe inaccuracy. While similar case dimensions might allow chambering, bullet diameter differences prevent safe interchangeability.

Chapters

  1. 00:00Introduction: Headspace Explained
  2. 00:51Compatible Cartridges in the .308 Family
  3. 01:31Baseline .308 Winchester Testing
  4. 02:25Testing .243 Winchester in .308
  5. 07:09.243 Winchester Results at 10 Yards
  6. 09:39Testing .260 Remington in .308
  7. 12:28Testing 7mm-08 Remington in .308
  8. 14:38Ballistics Gel & Conclusion

Frequently Asked Questions

What happens if you shoot .243 ammo in a .308 rifle?

Shooting .243 Winchester in a .308 rifle results in the undersized bullet causing significant gas blow-by, leading to extremely low velocities (around 1100 fps) and severe inaccuracy. The bullets will tumble and keyhole the target, rendering the rifle ineffective and potentially unsafe.

Can different calibers in the .308 family be safely interchanged?

While cartridges like .243 Win, .260 Rem, and 7mm-08 Rem share similar case dimensions and may headspace correctly in a .308 chamber, they are NOT interchangeable due to different bullet diameters. Firing them can cause bullet tumbling, gas leaks, and reduced performance.

What is headspace and why is it important for .308 Winchester?

Headspace is the critical distance that prevents a cartridge from moving too far forward in the chamber. For .308 Winchester, it's measured from the shoulder. Incorrect headspace, or firing a cartridge with incompatible dimensions, can lead to catastrophic firearm failure and serious injury.

Is it safe to fire 7mm-08 ammo in a .308 rifle?

Firing 7mm-08 Remington in a .308 rifle is not recommended and is unsafe for practical use. Although the bullet diameter is closer than .243 or .260, the bullets still tumble significantly, velocity is reduced, and accuracy is severely compromised. It should only be considered in extreme emergencies with extreme caution.

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