308 vs 7.62x51

[All Star]

Is there a difference?
I have both, and would really like to not blow up my rifle.

 

[honestlou]

There is a difference. Probably won't blow up your rifle, but to be 100% safe, use .308 in rifles chambered for .308, and use 7.62 in rifles chambered in 7.62. It is always a good idea to use the ammunition which is recommended by your firearm manufacturer. They almost always engrave it into the barrel or action so you know what you have.

 

[shrxfn]

If I remember right 308 chambers can shoot 308win or 7.62x51 but 7.62 cannot shoot 308 due to pressure levels. It is the opposite of 223vs5.56.

 

[falshooter]

Pressures are nearly identical.. Chambers are the issue

Most commercial ...headspaced .308 chambers are tighter then 7.62 chambered rifles due to the fluctuations of 7.62, most of being designed for military use. A longer chamber.. (headspace).. allows for chamber expansion when the barrel heats up during rapid and or continuous firing, assuring less extraction issues.
Most, if not all semi autos and bolt rifles will chamber and fire 7.62 surplus with no problems.
Some bolt rifles with match cut chambers will not even chamber ..some..7.62 ...again due to the varying case dimensions of 7.62 manufactures (mostly foreign)

Over 50 years of shooting, I've only had a cartridge headspace issue with only 1 ammo that was made in Syria

If your bolt rifle will close and lock on 7.62 ammo will the same force applied to close and lock on as your .308 ammo takes .... shoot it

 

[oneshy]

delete

 

[LouisianaJoe]

I reload both with H4895. I have a lot of L2A2 brass. L2A2 is a British standard that I the same as NATO. The Brass holds about 1 gr less powder than a .308. I separate the brass and I reload the L2A2 or NATO with 147-150 gr with 41.5 H4895. I get 1" 20 round groups with this at 100yds in my 1989 vintage M1A NM. I load 168gr TMK and 175gr SMK in .308 using re-15, Varget, and H4895 for My Remington 700 Police. I get Sub MOA groups with this. The .308 shoots good groups in the M1A but POI is slightly different and I do not want to change the scope settings that work so well with the L2A2 reloads.

 

[twinin]

I reload both with H4895. I have a lot of L2A2 brass. L2A2 is a British standard that I the same as NATO. The Brass holds about 1 gr less powder than a .308. I separate the brass and I reload the L2A2 or NATO with 147-150 gr with 41.5 H4895. I get 1" 20 round groups with this at 100yds in my 1989 vintage M1A NM. I load 168gr TMK and 175gr SMK in .308 using re-15, Varget, and H4895 for My Remington 700 Police. I get Sub MOA groups with this. The .308 shoots good groups in the M1A but POI is slightly different and I do not want to change the scope settings that work so well with the L2A2 reloads.

Nice work shooting an older M1A that well. You have it nailed down

 

[bayou06]

externally dimension wise, no. Internally, the 7.62x51 case is thicker, especially the web area at the base. This is for the hotter military ammo. Only real issue is if reloading, you'll need to dial back the load due to the internal dimension difference. As far a factory ammo, unless you are shooting an OLD 308 WIN, I'd probably pass on firing any 7.62 NATO in it, just to be on the safe side.