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Ive been reading on a lot of different forums about how the NATO cartridge and the .308 are in fact different sizes. But there has been no consensus on wether or not you can shoot NATO rounds in .308 guns and visa versa. I want to make sure that im not going to wreck my ltr. If someone could clear this up once anf for all that would be great.
 

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I have heard that as well. Also heard .223 and 5.56 are not the same round. While I have herd many "experts" tout this I have never herd exactly how they are diffrent. Shoot your .308/ 7.62 ad don't fret about it. IF there is a diffrence, that I doubt, there is not enough to make a diffrence. I do know military ammo is loaded to full power and commercial ammo in the US is down loaded for legal liability. Get some Laupa and US mfg loads with the same bullet weight and you will probably be able to tell a diffrence with a chonograph if not recoil.
 

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7.62*51mm NATO = .308 Winchester
you can fire 7.62mm in a .308 and .308 in a 7.62mm

same with its smaller relative- 5.56*45mm NATO
the only difference being i hear you shoudlnt fire 5.56mm in a .223 but its ok to fire .223 in a 5.56mm
i honestly dont know, dont own anything chambered in .223, only 5.56mm if there is a difference
 

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The real differences are mostly brass, primers, and pressures I think.

The military uses thicker brass, and the SAAMI specs for pressures between civilian and military rounds are different. I think 308 Win could be loaded hotter than the 7.62x51mm Nato. Primers on military rounds are tougher and harder too.
 

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OK guys here goes. The chamber drawings for 308 and 7.62X51 are different, the rounds are not the same. That being said, most times 7.62X51 will work in 308 chambers and vice versa. Short or tight match Chambers on 308 rifles will not like all NATO ammo. My 700 with a newly cut minimum Spec Chamber hates the south african ammo, but put any commercial 308 or Match NATO ammo in it and it works fine.

I learned this while working on M14s, an M14 is a prime example of a NATO Chambered weapon. The Nato Chamber is longer in the Throat portion, here are the Headspace gage settings on 308 VS NATO

Nato

Go=1.635
No Go=1.6405
Reject=1.645


308Win

Go=1.630
No Go=1.635
Reject=1.638


So there is why some NATO ammo is hard to chamber in a 308, but again much of it will work, just be careful and if you have problems dont use it. Hope this helps.
 

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mlammers is in fact correct. (like that wasn't obvious). I've only ran into problems a few times, like when reviewing the HS Precision HTR2000, I tried some M118 which would not chamber. The 308 match chamber on the HS was just too tight for it.

MEL
 

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And as for 5.56mm vs. .223, the 5.56mm has a longer leade (throat).

The 5.56mm is also loaded to higher pressures.

So....

If you fire 5.56mm ammo in a .223 chamber, pressures will rise rapidly. Firing hotter ammo in a tighter chamber will do that. SAAMI considers it unsafe to fire 5.56mm ammo in a .223 chamber.

But it is safe to fire .223 ammo in a 5.56mm chamber.


Mad.
 

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So, based off of what mad just stated, I wonder how safe the Federal and Winchester (among others) XM193 ammo is in civilian .223's. I ask because that ammo is available for civilian purchase

MEL
 

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If that ammo is marked, "5.56mm", do not shoot it in a .223 chamber. If the ammo is labelled ".223", then you can shoot it in either a .223 or a 5.56mm chamber.

In 1978, SAAMI issued a warning about using 5.56mm in a .223 chamber. They went so far as to call it "an unsafe combination".

See: http://www.saami.org

If you are thinking about getting an AR-15, get one with a 5.56 chamber. Bushmaster, Colt and RRA, (among others) are all available with 5.56 chambers.

Mad.
 

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Thanks for the info. I have heard they are diffrent for years, but no one seemd to be able to give a good answer. In fact one guy acted like I was the village idiot for asking how.I don't think he knew how they were diffrent, he was just letting everyone know how smart he was knowing they were.
 

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Yeah, thanks Mad. I was confused by that issue some. Now I know to go for the 5.56mm chamber
 

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Due to the very issue that Mad addressed, most AR rifles are made with a 5.56 chamber standard, you acutually have to order a 223 Wylde Chamber or 223 remmy chamber to get the civilian spec chamber. I will verify the chamber spec on remmy bolt guns, but I think the 700 police models are 223 spec not 5.56.
 

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Actually, AR barrels can be had with either chambers. So when you buy an AR, be careful to get the chamber that you really want.

All Bushmaster chrome lined barrels have 5.56 chambers. But their stainless barrels are reamed for .223.

Rock River Arms chrome lined barrels have the 5.56 chamber, but some of their barrels have the Wylde chamber or the .223 chamber. The Wylde chamber is a chamber with a throat longer than .223 but shorter than 5.56mm. Apparently you can use 5.56 and .223 in a Wylde chamber. Mr. Wylde was one of the early gunsmiths who accurized the AR back in the mid 80s.

This whole confusion over 5.56 and .223 is why you ought to only buy quality parts from an experienced dealer. That's the only way you can ever be truly sure what you are getting. If you buy a 5.56 barrel from Joe Schmoe, you may find yourself getting a .223 instead.

And there is nothing wrong with a .223 chamber as long as you only use .223 in it.


Mad.
 

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mlammers said:
Nato

Go=1.635
No Go=1.6405
Reject=1.645


308Win

Go=1.630
No Go=1.635
Reject=1.638
So, would this mean that the 7.62 ammo "could" be more accurate in a rifle chambered for a .308, given the fact that the head spacing is tighter?
 

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Yep, but it also means it could...

Fail to feed

Fail to extract

Cause a pressure spike
 

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never had a fail to feed happen from 7.62 in a .308 weapon but i have seen inconsistant groups aspecially when you get a bad lot of 7.62
 

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I've used M118LR & M118 in various 308 chambered rifles, only the HS gave me problems.... so I have to say yes, I've had a failure to feed. (well, failure to chamber)

MEL
 

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No extraction problems from anyone yet? Maybe it was Mlammers who posted that...With things being extra snug already, it would make sense as the case puffs out some.
 

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Yes, it was me, I had to beat my 700 open using the South African 7.62 Ammo in my 308. Mine has a tight minimum spec chamber, which combined with hot ammo lead to case puffing up some. It kicked like a mule too, and had very loud report. Obviously the pressure was up some, as the primers were flattened too.
 

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Ah yeah, I remember now. We were speculating it was MG ammo.
 
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