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I've been hearing that the 5.56x45mm and the .223 Rem cartridges are not exactly the same. Also the 7.62x51mm and the .308 have the same issue too. Can someone help me shed some light into this? Thanks.
 

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They're just different names (metric vs. english) for the same cartridges. Dunno who's been telling you they're different...
 

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Well, he's actually correct. While they are nearly identical, they have slightly different accepted overall lengths. (the brass is actually the same). So on occasion, you might get a round that doesn't chamber in the other. (Its extremely rare as 99% of all the ammo out there is loaded to the same specs, its usually only a problem on very rare occasions of loading military ammo in civilian rifles, but like I said, its pretty much a non existant problem any more). So feel free to shoot 7.62 in .308 rifles and visa versa

MEL
 

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ive herd dont shoot 5.56mm in a .223 but its ok to shoot 5.56mm and .223 in a 5.56mm
the reason being is 5.56mm (military ammo) is loaded to a higher pressure and will beat up guns chambered in .223
 

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Just as Mele stated with the 7.62 and .308, the 5.56 and .223 are interchangeable. You may run into an occasional problem if you have a weapon at one end of the tolerance spec and ammo at the other end, but that is exceptionally rare and will usually result in chambering difficulties and not an over-pressure situation.. Military ammo will vary more in pressure than commercial ammo because of (1) greater liability issues for commercial manufacturers and (2) the private sector has a choice as to what ammo it uses so commercial ammo must be of higher quality to drive sales. This is why commercial ammo will usually out-perform military ammo for accuracy. You may have problems over time if you are using a semi or full-auto weapon with bullets that are heavier than the design standard. This can eventually damage the operating system in some weapons (prolonged use of 180-200 grain bullets in an M-14 or M1A for example). If your weapon is in good condition and the ammo comes from a reputable source, I wouldn't worry whether the headstamp says .223 or 5.56.

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I have run into this issue int he past... Someone goes and gets a ton of 7.62 millitary brass, he then goes home reloads a bunch using long action dies (he owns a bolt action) then when he tries to chamber a round in his bolt action rifle, they round just wont fit in there at all, most of the time the military rounds are shot through say a M14 or perhaps an M60 where the chamber has a lot more play than with a bolt action and so the brass tends to swell a lot more especially around the neck, which is what i have realized causes the main part of the problem, some people say resize using a short stroke die since i t resizes the whole case, however i havnt tried this but everyone i have ever talked to says a short stroke die for reloading for a bolt action is a bad combo...
 

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I've been reloading for decades and haven't heard of "short-stroke" and "long-stroke" dies for a given chambering. Maybe you're using a terminology that is different from what I am accustomed to. What you are describing sounds like the difference in neck-sizing (prefered for bolt-actions) and full-length sizing (preferred for semi and full-auto). These differences can be affected by adjusting the die in your press according to your preference and your weapon's specific dimensions. There ARE dies that are specifically neck-sizing dies as well as dies that are geared towards benchrest shooters, but stroke length is not what differentiates them. When reloading ANY case, you need to check the overall case length AFTER re-sizing to insure that it does not exceed standard specs. You will also need to check inside and outside neck dimensions to insure that the wall thickness is within spec. When going through the process of firing and then resizing, the brass in a case has a tendency to flow forward resulting in the thickening and/or lengthening of the case. You must trim and/or ream the case to correct this condition to bring the case back into spec. When reloading military brass, you should also be sure to ream the primer pocket to remove excess metal left behind by the military crimp. Commercial ammo will not have this crimp on the primer. Hope this helps.

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Didn't the SS109 round have a longer, heavier bullet over the M193? Might that be an issue in terms of chambering a round?
 

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CM2k said:
Didn't the SS109 round have a longer, heavier bullet over the M193? Might that be an issue in terms of chambering a round?
All standard chamberings have internationally honored standard specifications on dimensions and operating pressures that manufacturers adhere to. Overall loaded cartridge length is one of the specifications that fall within that standard. When a heavier (longer) bullet is loaded in a given cartridge, the extra length will result in deeper seating of the bullet and NOT greater overall cartridge length. This also reduces the available capacity for powder. The need to balance pressure, velocity, external dimensions and accuracy will dictate an upper limit on bullet weight for a cartridge.

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mrotherstuff said:
I've been hearing that the 5.56x45mm and the .223 Rem cartridges are not exactly the same.
From http://www.saami.org

CENTERFIRE RIFLE

In Rifle Chambered For -------- Do Not Use These Cartridges
223 Remington ------------------ 5.56mm Military


From http://www.thegunzone.com/556v223.html

"NATO chambers (5.56) have a long leade. SAAMI chambers (.223) are tighter and have a short leade. SAAMI chambers are designed for increased accuracy, but will yield dangerously high pressures in guns using military ammunition"
 

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talking_target said:
So what SAAMI said for the 5.56 vs. .223 also apply to 7.62 vs. .308?
7.62 vs. .308 doesn't seem to have the same problem according to SAAMI.

From http://www.saami.org

CENTERFIRE RIFLE

In Rifle Chambered For -------- Do Not Use These Cartridges
308 Winchester------------------ 7.62x39
------------------------------------300 Savage

jlb
 

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Military ammo in civilian guns

I have two AR15's both have had many many Military rounds thru them. Green tip, 55gr ball, 69gr sierra. Never a malfunction with any ammo.
Gerald :?
 

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While the cartriges actually do fit (both 223 <-> 5.56*45 and 308 <-> 7.62 NATO) the pressure maximums are different; and the pressure measurements are different (CUP vs PSI).

Do not shoot 5.56 ammo in chambers labeled 223. It is OK to shoot 223 in chambers labeled 5.56

Do not shoot 308 in chambers labeled 7.62. It is OK to shoot 7.62 in chambers labeled 308.

Can one get away with this:: sure for hundreds or even thousands of rounds. But it may come back and bite you. So if you choose to do this you are accepting the associated risks.
 
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