You can shoot a 7.62 round in a .308 barrel, but not the other way around. However, it’s always best to use the ammunition recommended by the manufacturer because your rifle may explode. To check the caliber of your firearm, inspect the barrel for a stamp.
Read on to learn more about the 308 barrel and whether or not you can use 7.62 cartridges like the 7.62 Nato and the 7.62×51 with it.
Should You Shoot 7.62 Out of a 308?
Just because you can do something doesn’t mean that you should.
When questioning if you should shoot a 7.62 out of a 308, check the manufacturer’s notes of your current model for the most accurate information about what bullets to use for your particular barrel. The worst-case scenario is the rifle explodes, causing serious injury to you or those around you.
You can avoid this possibility by simply using the recommended cartridge for your gun. Inspect your barrel if you don’t know what caliber your gun is; It should be stamped right on the side.
A less serious problem that you might encounter when using the wrong kind of ammunition is that it can cause your gun to jam or have feeding issues. This will reduce the quality of your shooting experience because struggling with these problems can be a pain when you just want to have fun.
Still, using the wrong cartridge might also damage the gun. Repairing firearms can be expensive, and sometimes it’s even impossible, so be extremely careful about what cartridge you use.
Ultimately, not using the recommended ammunition could permanently affect the performance of your firearm. You may find that it’s less accurate or more difficult to control.
7.62 vs. 308: What’s the Difference?
The difference between 7.62 Nato and 308 cartridges is that the 308 cartridge has a thinner casing, so it can hold more grains. However, these cartridges look so similar that you might not be able to tell the difference unless you have a trained eye.
As seen in the table below, the dimensions of the casings are identical from the outside. In fact, the 7.62 cartridge case was developed using the 308 cartridge’s design, which is why they look the same!
However, the 7.62 has a smaller case capacity, so the maximum pressure is less than the 308. Here’s the data:
|7.62 Nato Cartridge||308 Cartridge|
|Casing Length||51.2 mm (2.015 in)||51.2 mm (2.015 in)|
|Rim Thickness||1.3 mm (0.050 in)||1.37 mm (0.0539 in)|
|Overall Length||71.1 mm (2.800 in)||71.1 mm (2.800 in)|
|Case Capacity||52 grains||56 grains|
|Maximum Pressure||58,000 psi||62,000 psi|
Can You Shoot 7.62 NATO Out of a 308 Barrel?
You can shoot a 7.62 NATO out of a 308 barrel because the 7.62 bullets have a smaller maximum pressure than the 308 cartridges. There’s little to no risk of damaging yourself or your rifle since the 308 barrel can withstand the pressure of the 7.62.
Clint Morgan from Classic Firearms explains that the performance of these cartridges makes all the difference when determining what bullet can be fired from what gun.
The 308 generates more pressure than the 7.62 because the 308’s case is a bit thinner than the 7.62. In this way, the 308 can hold 56 grains of powder as opposed to the 7.62’s 52 grains, which increases the pressure buildup when fired.
As noted in the table in the previous section, the 7.62 Nato cartridge has a maximum pressure of 58,000 psi, while the 308 cartridge has 62,000 psi.
The 308’s pressure can be dangerous when shooting a 308 cartridge out of a 7.62 barrel because you could damage your rifle, but shooting a 7.62 out of a 308 barrel will be perfectly fine.
Watch Clint explain more about this in the video below:
Can You Shoot 7.62×51 Out of a 308 Barrel?
It seems that you can shoot 7.62×51 out of a 308 barrel, as few people have reported issues when doing so. Certainly, a 308 barrel is sturdy enough to handle the minimized psi. However, they’re different enough that you shouldn’t shoot a 308 cartridge out of a 7.62 barrel.
Similar to the 7.62 Nato, the 7.62×51 has a thicker casing than the 308, so it can’t hold as many grains. This means that shooting a 308 cartridge out of a 7.62×51 barrel will have the same problems as the 7.62 Nato barrel.
Again, before attempting to fire either of these cartridges from your 308 barrel, contact your rifle’s manufacturer to double-check. Every rifle and every caliber are different, so it’s best to get the okay from an official source.
Is It Okay To Shoot a 7.62 From a 308 Long Term?
It’s not okay to shoot a 7.62 from a 308 long term, as you risk several problems, including fit and an incorrectly gassed rifle. Even though the 308 barrel can handle the psi, it’s not recommended to shoot 7.62×51 or 7.62 Nato cartridges from a 308 for extended periods.
The following issues could have negative effects on your rifle and shooting experience.
Overgassed or Undergassed Rifle
The main issue is that if your gas system isn’t tuned correctly, your rifle may fail to cycle the action. You’ll experience harder recoils and a less user-friendly experience overall.
Having an incorrectly gassed rifle can cause extra stress and wear on your rifle, so it’s more important than ever to make sure that your rifle is properly gassed when you’re shooting a caliber that was not made for your rifle.
If you’re going to shoot a caliber like the 7.62×51 or the 7.62 Nato from a 308 barrel, ensure that your rifle is properly gassed, so you don’t permanently damage it over time.
Here’s how to tell if your rifle is overgassed or undergassed using the clock method:
- Aim down the range. (This direction is 12 o’clock, and your right is 3 o’clock.)
- Fire your rifle several times.
- Notice the direction that the casing flies during extraction.
If your rifle is overgassed, the casing will fly anywhere from 1 o’clock to 2:45.
If the casing flies in the 3 to 4 o’clock range, your rifle is gassed just fine.
If your rifle is undergassed, the casing will fly anywhere from 4 to 6 o’clock.
Surplus Ammunition Issues
Surplus ammunition is inexpensive, so it’s great for practice. However, it’s best to be careful about what you buy.
Surplus ammunition is older, so the primer is made of potassium chlorate, which has a corrosive factor. If you use this kind of ammo, you may find the need to clean your gun completely after every outing because of its corrosive nature.
I recommend not buying surplus ammunition online. Before purchasing any surplus ammunition, it’s best to go in person so you can make sure that there’s no sign of water damage on the box, casings, and wrappings.
Still, there’s not a surefire way to tell if the rounds have been stored properly, so you might find that some rounds are unsafe to fire or don’t fire at all.
In the end, surplus ammunition was not intended for civilian use, so if it wasn’t taken care of properly while it was sitting on the shelf, you run the risk of hurting yourself, your rifle, or others around you while firing it.
Complications With Fit
Some 7.62 cartridges are a tight fit for the 308 barrel, so you might experience some malfunctions. Loading issues may occur if the cartridge dimensions are too big for your rifle.
At the same time, you might face extraction issues for the same reason. Jamming is no fun, so simply use the cartridge designed for your rifle to reduce the chance of that.
On the other hand, your bullet will fly haphazardly and inaccurately if your cartridges are too loose of a fit. This is because your barrel can’t hug the bullet enough to launch it accurately. All of that extra space around the bullet makes a huge difference.
Most gun owners report that the 7.62 and the 380 cartridges are more-or-less interchangeable, as modern rifles can handle the differences in pressure between the two. Keep in mind, however, you shouldn’t use any ammunition not specified by your rifle’s manufacturer, and you have a higher chance of injuring yourself or ruining your rifle if you shoot a 7.62 out of a 380 barrel.
So, for safety concerns, I don’t recommend that you venture there without first contacting your rifle’s manufacturer to see what they say.
For more, check out How Much Does Ammo Cost? | Detailed Price Analysis.
Christian grew up in the Ozarks where he spent much of his childhood on his grandparents’ homestead learning about guns, hunting, and the great outdoors.
An avid traditional bowhunter, much of his writing covers this and other similar topics, but he also covers just about everything from history and economics to motorcycles.
See more of his work at ChristianMonson.com.