7.62 NATO vs. .308

[SPOOK331945]

Has anyone had any experience loading 7.62 NATO? I have a 1919a4 chambered in it so needless to say it can get expensive quick. I know there are slight variances in the case shoulders of the two. Due to that difference the 1919 likes to split .308 cases.... (some rounds got mixed in with my 7.62 one time.. and it DOES NOT like them.. whoops..) Me personally I haven't seen any case specific 7.62 resizing dies, I've never attempted to reload 7.62 but have reloaded .308 from time to time. Any knowledge would be appreciated.

Been a few years since I've really reloaded a lot, got the bug to get set back up. Boxed everything up when I moved and haven't messed with it since.

 

[bstewrat3]

The pressures on 308 Winchester are significantly higher than for 7.62x51, 62,000 vs 50,000 and the headspace for 7.62x51 is slightly longer which could account for the splits. The difference in case thickness is mostly at the case head not the shoulder junction. Neck thickness variation will be similar to what you would find between brands of commercially loaded ammo. Reloading dies are the same, but through changing of expanding buttons can be tailored to your needs.

 

[russc2542]

The pressures on 308 Winchester are significantly higher than for 7.62x51, 62,000 vs 50,000 and the headspace for 7.62x51 is slightly longer which could account for the splits. The difference in case thickness is mostly at the case head not the shoulder junction. Neck thickness variation will be similar to what you would find between brands of commercially loaded ammo. Reloading dies are the same, but through changing of expanding buttons can be tailored to your needs.

I thought the pressure difference was from one standard being measured CUP and the other by transducer, which have about that difference in measurement thus the actual pressures are pretty close.

dimensions, yes those are different.

If you want to get technical, 7.62 also has a lot more specs on projectiles, primers, sealing cases, etc.

 

[BigMoose]

Machine guns are also known for REALLY loose chambers too. So I expect it is on the long end for the 7.62 Nato spec to boot.

Add to the fact that commercial brass is thinner..

Thus you get the the splits!

 

[bigedp51]

There is less than 2,000 psi difference between the .308 and 7.62 NATO with the .308 being loaded slightly warmer.

"BUT" for practical purposes the .308 and 7.62 are one in the same cartridge.

And as stated above the confusion is caused by the method of measuring the chamber pressure, meaning transducer psi or copper crusher cup.

The Lake City 7.62 cases are made thicker and have approximately 2 grains less of H2O capacity.

Cartridge Pressure Standards

Case Capacities

 

[Robert Richardson]

Dies are the same, just load them to 7.62x51 specs and not .308 Winchester.

 

[bigedp51]

Don't forget that the military 30-06 in the M1 Garand and the 7.62 in the M14 and M16 were loaded to specific port pressures function properly.

Meaning the higher pressure 30-06, and .308 commercial ammunition could damage the op rod without a adjustable gas plug using slower burning powders. And the reason for slightly lower chamber pressures in service rifles.

So again the only difference between the .308 and 7.62 is the European "metric" designation. And the European CIP considers both cartridges to be one in the same.

The M1 Garand and Commerical Ammunition

M1 Garand Ammunition and the Ported Gas Plug

 

[Robert Richardson]

Google 7.62x51mm service rifle loads. Lots of good information. I use 150gr FMJ, Lake City cases with 42.5grs IMR 4895.