You shouldn’t shoot a .308 Winchester in a 7.62 rifle. The .308 Winchester’s cartridge is slightly shorter than the chamber of a 7.62 rifle. When fired from a 7.62 rifle, the .308 Winchester’s cartridge can split in half and expel hot gasses, which can be dangerous.
While it may be tempting to use commercial .308 Winchester ammo in a 7.62 rifle, you should avoid this at all costs.
What Are .308 Winchester and 7.62 NATO?
The .308 Winchester and 7.62 NATO are popular rifle ammunitions used by hunters, military personnel, and target shooters. The 7.62 NATO follows the general design of the .308 Winchester but has a thicker wall construction, allowing it to generate higher pressures when fired.
Although often confused for one another, the .308 Winchester and 7.62 NATO ammunitions have some important differences that impact their performance and application.
Are .308 Winchester and 7.62 NATO the Same Caliber and Interchangeable?
The .308 Winchester and 7.62 NATO have the same caliber and are interchangeable if you’re firing a .308 rifle. The two ammunitions feature the same bullet diameter at 0.308 in (7.8 mm). However, you should not fire a 7.62 rifle with .308 Winchester ammo.
Here are the key differences between the two ammunitions:
- They don’t have the same brass thickness. The 7.62 NATO has a thicker brass casing yet retains the same external dimensions as the .308 Winchester. This thicker brass allows the 7.62 NATO to generate higher pressure and stretch in the chamber more with less risk of bursting.
- They differ in pressure capacity. The .308 Winchester is loaded to a higher pressure than the 7.62 NATO, with a slight difference of 2,000 PSI.
- They have slightly different chamber dimensions. The .308 Winchester headspace is 1.630 in (4 cm), while the 7.62 NATO measures closer to 1.6405 in (4.1 cm). The chamber dimensions matter because the cartridge stretches and bursts when fired. Military rifles are designed with larger chambers to prevent jamming during rapid firing.
- They weren’t specifically developed for the same chamber. The .308 Winchester was developed by the Winchester Repeating Arms Company primarily for hunting and personal protection. The 7.62 NATO, on the other hand, was created by NATO for combat use. Both rounds are based on early military calibers but slightly differ in their construction, pressure levels, and overall function when fired.
- They don’t have the same powder load. The .308 Winchester has a slightly higher powder load, which affects its performance when fired from a rifle with a longer barrel length.
This YouTube video explains the difference between these two ammunition types:
What Happens When You Chamber a .308 Winchester in a 7.62 Rifle?
If you chamber a .308 Winchester into a 7.62 rifle, it will fit, but there could potentially be dangerous consequences. The pressure generated by firing the .308 Winchester round out of a 7.62 rifle can exceed its recommended levels, leading to an increased risk of damage, injury, or both.
When using a .308 Winchester, remember that you should only use it in firearms chambered for the same caliber. Trying to fire a .308 Winchester from a 7.62 rifle or any other type of firearm is likely to lead to injury. Additionally, you should not use ammunition loaded with higher pressure rounds or heavier bullets with rifles chambered for the .308 Winchester due to potential damage or operational issues.
What Happens When You Fire a .308 Winchester Ammo?
Firing a .308 Winchester ammo generates pressure that forces outwards against the cartridge casing walls and the bullet itself. Gases propel the bullet through the barrel at high speeds, making its way toward the target.
A .308 Winchester ammo is a cartridge made of three parts: the primer, propellant, and bullet. The firing process begins with the action of pulling the trigger mechanism, which sets off a small explosion inside the cartridge.
This small explosion occurs when the propellant in the cartridge is ignited. The propellant is the engine that powers the bullet through the barrel, then out of the gun. In front of the cartridge is the actual bullet that flies through the air to hit the target.
Why Can’t 7.62 Rifles Shoot Just Any Ammunition?
A 7.62 rifle cannot just shoot any ammunition because the size of the cartridge matters. The barrel of a 7.62 rifle must be able to contain and then propel whatever ammunition is loaded in it. If the ammo is too big or too small, it will not fit properly and won’t fire correctly or at all.
The caliber is the diameter of a firearm’s chamber. Because guns have specific caliber measurements, you cannot shoot bullets that won’t fit the chamber. You will usually find the caliber marked on the side or barrel of the receiver.
What Rifle Shoots .308 Winchester Ammunition?
The .308 Winchester Semi-Automatic shoots .308 ammo. It’s a popular choice among hunters, homeowners, and law enforcement. It’s reliable, accurate, and powerful enough to take down most midsize games.
The .308 Winchester short-action rifle is excellent for military use. However, the inexpensive ammo and the rifle’s success in hunting big game have made it an all-around excellent hunting rifle.
What Rifle Shoots 7.62 NATO Ammunition?
Several rifles shoot 7.62 NATO ammunition. The FAL battle rifle, US M14, M60, M240, M40, and M21 use this ammunition. This ammunition is standard for the NATO (or military) rifle and is the most commonly chambered ammunition worldwide.
What Factors Affect Caliber Size?
The main factors that influence what caliber size should be used are the type of firearm you’re using, the purpose for which you intend to use it, and personal preference. The most commonly used caliber sizes include 22 caliber, 38 caliber, and 45 caliber.
The caliber size is the gun barrel’s diameter, which corresponds to the cartridge. It affects the power of the round, the recoil felt when firing, and the accuracy of shots. Different guns require different calibers depending on what they are being used for.
Aide from the firearm you’re using, it’s important to consider these two main factors when choosing caliber size:
- The range at which you plan to fire your weapon. Short-range shooting requires low-velocity cartridges that produce less recoil than long-range shooting does.
- Intended use. If you’re hunting game animals, you want enough power in your cartridge to penetrate deeply but not so powerful as to cause excessive damage.
Is There a Difference Between Large and Small-Caliber Ammunition?
There are several significant distinctions between large and small-caliber ammunition. Large-caliber ammo has the following characteristics:
- It has more stopping power, enabling it to kill with one shot.
- It delivers more accurate shooting versus the “pray and spray” method.
- It can penetrate body armor better.
In contrast, small-caliber ammunition has the following characteristics:
- It is not meant for shooting to kill but more for wounding to buy time in battle.
- Smaller caliber ammo weighs less, so shooters can carry more rounds.
- Small-caliber ammunition with good ballistics can be as effective as large-caliber ammunition.
Firearms ammunition can be confusing but ultimately comes down to choosing the ammunition recommended by the gun manufacturer. As you become a more experienced shooter, the slight differences among the various ammunitions will make sense. Then, you can use your judgment and the expert opinions of trained shooters when choosing which ammo to use in your gun.
For more, check out How Much Does Ammo Cost | Detailed Price Analysis.
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Hey, I’m Jim, and I’m the author of this website. I have been teaching people a wide variety of survivalism topics for over five years and have a lifetime of experience fishing, camping, general survivalism, and anything in nature. In fact, while growing up, I spent more time on the water than on land! I am also a best-selling author and have a degree in History, Anthropology, and Music. I hope you find value in the articles on this website. Feel free to contact me if you have any questions or input!