The difference between .308 and 7.62×51 is a fun conversation to have. Today, we are gonna show you some of the differences that will help you to clear up the confusion.
The 7.62×51 was first created to increase the effectiveness of the M1 Garand 30-06 model of that time. It was the modified version of 300 Savage which was called by T65.
This came to be known as 7.62×51 later. The commercial market wanted in this round so, Winchester introduced the popular .308.
It is almost impossible to tell the difference between .308 and 7.62×51 just by looks and weight alone however certain measurements can tell a different story.
The 7.62x51mm nato has a thicker wall than a 308 however, 308 has a higher pressure. Some industry folks say that there is a 4000 psi difference while others say that there is as much as 12000 psi difference.
It is safe to shoot the 7.62x51mm nato rounds out of the 308 barrel however, you can not say the same for shooting the 308 out of the 7.62×51 barrel.
The issue here is the headspace, which is the distance from the bolt face to the point of the chamber that stops forward motion of the cartridge case.
A lot of military rifles have a longer chamber which creates a longer headspace. The higher pressure and thin walls of 308 could cause some major issues.
It is also important to know that most new rifles have headspace which allows both types of ammo.
However, it’s still smart to check your rifle specs to make sure that you can shoot 308 ammo in a 7.62×51 rifle barrel just in case that it has a long chamber and excess headspace. Another difference between .308 and 7.62×51 is their dimensions.
The no go length of the Winchester 308 is 1.634 inches while the 7.62×51 comes with a length of 1.6405 inches.