Need some schooling on ammo 7.62X51 VS .308win
- Thread starter micromind
- Start date
The brass is thicker on military cases. Outside dimensions are the same, I have mic’d them many times. The difference between the two is the chamber dimensions. 7.62X51 chambers have looser tolerances for reliability reasons.
I have had military 7.62 rifle barrels in bolt guns, you can use .308 brass. I used Winchester and later Lapua. There is alot of confusion out there because of battle rifle specs.
Don’t shoot new commercial .308 ammo in an old small ring mauser or a converted enfield, its too hot.
I have had military 7.62 rifle barrels in bolt guns, you can use .308 brass. I used Winchester and later Lapua. There is alot of confusion out there because of battle rifle specs.
Don’t shoot new commercial .308 ammo in an old small ring mauser or a converted enfield, its too hot.
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- Location
- Maple Ridge, BC
I believe it has to do with case pressure and the assumed capacity of the barrel/chamber to safely handle it. There is a difference and from what I've read the 308 pressure is higher than the military spec of 7.62x51.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
You'll be fine. Same with .223/5.56. Just shoot it.
redshooter
CGN Ultra frequent flyer
- Location
- Central Ontario
Ok, here it is...
7.62 NATO Ball (147-150 gr) is loaded to lower pressures. than .308. You can shoot any 7.62 NATO Cartridge in any .308 (see above for an exception...). If you have an older Battle Rifle like an M-14/M-305/M1A it's a very bad idea to shoot .308 Win with Projectiles heavier than 178 gr. Also burn rate is an issue with M-14 type rifles.
All this confusion comes from 5.56 NATO vs. .223 Rem. The only real difference between these two is chamber dim., esp. the throat, it's longer (5.56). If you are shooting 62 gr Ball in an older .223, or one throated for light bullets you could have pressure issues...but since it won't stabilize in a 1 in 12 (or 1 in 9 for that matter) why shoot it.
So, as a loose rule no .308 in the 7.62, and no 5.56 in the .223. If it's a recently made .223 with a 1 in 9 twist, or something like an AR-10/102 they are interchangeable.
7.62 NATO Ball (147-150 gr) is loaded to lower pressures. than .308. You can shoot any 7.62 NATO Cartridge in any .308 (see above for an exception...). If you have an older Battle Rifle like an M-14/M-305/M1A it's a very bad idea to shoot .308 Win with Projectiles heavier than 178 gr. Also burn rate is an issue with M-14 type rifles.
All this confusion comes from 5.56 NATO vs. .223 Rem. The only real difference between these two is chamber dim., esp. the throat, it's longer (5.56). If you are shooting 62 gr Ball in an older .223, or one throated for light bullets you could have pressure issues...but since it won't stabilize in a 1 in 12 (or 1 in 9 for that matter) why shoot it.
So, as a loose rule no .308 in the 7.62, and no 5.56 in the .223. If it's a recently made .223 with a 1 in 9 twist, or something like an AR-10/102 they are interchangeable.
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I have a Savage bolt gun in .233 with a 1 in 9 twist . I tried some 5.56 without realizing it might be a problem and the bullets were getting jammed into the lands to the point where extracting an unfired cartridge pulled the bullet out spilling powder everywhere.
.223 of all kinds works great.
So I'd suggest staying away from 5.56 in a true .223 chamber.
.223 of all kinds works great.
So I'd suggest staying away from 5.56 in a true .223 chamber.
redshooter
CGN Ultra frequent flyer
- Location
- Central Ontario
I'm curious, what projectile? I ask because there is no way your throat should be short enough to have any 5.56 factory load jam the lands. As far as I know no one is loading 5.56 long as it has to fit in a STANAG mag.
If you compare maximum pressures using comparable methods, the difference between 7.62 NATO and .308 is either nothing or minimal. CIP .308 and 7.62 NATO are the same; SAAMI .308 is slightly higher, all using transducer pressure tests. The idea that there is a significant difference comes from confusion between copper crusher and transducer test values. Copper crusher tests always give lower values than transducer tests.
Some 7.62 NATO firearms (e.g. M14s) may have headspace that is still in spec, but is excessive by .308 standards. This is not conducive to good case life for reloads, but is highly unlikely to cause catastrophic failure.
Some 7.62 NATO firearms (e.g. M14s) may have headspace that is still in spec, but is excessive by .308 standards. This is not conducive to good case life for reloads, but is highly unlikely to cause catastrophic failure.
It was Independence 5.56 XM193I. For comparison, I have no problem with Hornady Steel Match 75gr.
From what I understand the 5.56 chamber has a longer leade with a shallower taper, so depending on the shape of the projectile it's conceivable that a cartridge that fits in a 5.56 chamber might jam the lands on a .223 chamber.
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