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| Member |
7.62 ammo x .51 in a .308 Win. rifle = fine just fine .308 in 7.62 x .51 = no way and .223 ammo in 5.56 x .45 rifle = ok 5.56 x 45 in a .223 = not recommended Unless otherwise stated in the manual that came with the gun.This message has been edited. Last edited by: bendable, Safety, Situational Awareness and proficiency. Neck Ties, Hats and ammo brass, Never ,ever touch'em w/o asking first | ||
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| Member |
As a general rule of thumb, yes, you are correct. I don't have my data on-hand right now, but IIRC, this advisement is primarily based on specs for max pressure ratings for the different cartridges. Someone may come along with the actual figures, but I recall that the 7.62 x 51 also had to accommodate M60 machine guns and similar automatic weapons, and these systems were not as forgiving for higher pressures, such as is spec'd for .308 Win sporting rifles. I have also read that the preference when buying an AR10 platforms is .308, vs. 7.62, to keep options open regarding ammunition selection, but I don't own one and have no direct experience. For my Bula M14 build, when finished I don't think it will matter, as Bula headspaced the chamber when they installed the barrel to accommodate a range of commercial ammunition and pressures. It does get a little confusing, as you point out, that the inverse is true when comparing the 5.56 and .223 Remington cartridges. Without doing some research, though, I can't say that this is strictly due to the pressure differences. There has to be more to it than that, based on the advertised advantages of selecting a Wylde chamber in the AR15 platform, which is promoted to accommodate both 5.56 and .223. My Rock River has the Wylde chamber, and I have had no issues with any of the ammo I have purchased. | |||
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Hop head  |
headspaced or cut the throat for a variety of rounds? overall I read a lot of conflicting info on the internet, regarding both calibers, some folks seem to confuse headspace, throat and pressures, personally , I have run a lot of M193 5.56 ball thru my Mini14, and some folks would swear I would have blown it up by now, but it is running fine and undamaged https://chandlersfirearms.com/chesterfield-armament/ | |||
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| Member |
I was told that they "headspace" the actions and rifles at 1.633-1.634 and have been able to run all commercial 308 and 7.62 NATO with that setup. I purchased the receiver, barrel and bolt assembly from them at the same time, so they had the necessary components to perform this operation. | |||
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| Member |
SAAMI has a chart of unsafe cartridge combinations. There is a link to download it, on the bottom left. You'll notice SAAMI says 5.56mm military is not to be used in .223 chambered rifles. I didn't see anything on .308 or 7.62, nor do I profess any expertise on it as my personal rifles are all .308 and fed commercial .308 and service weapons are all fed USGI 7.62mm via the supply system. Understand that there is a lot variations across chambers and cartridges based on a number of factors. | |||
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| Member |
The external case dimensions of 308Win and 7.62x51 brass are the same, but commercial brass is typically thinner than military brass. A problem can arise in some military weapons with chambers on the long side of the headspace spec when commercial ammo is fired in them, especially if it's a hotter load. It's not a given that there will be a problem, but it can result in a case head separation. | |||
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Age Quod Agis |
Mini's are specifically approved by Ruger for both .223 and 5.56, so you are well within manufacturer's specs. M1A are also approved by Springfield for both commercial .308 an 7.62 Nato. "I vowed to myself to fight against evil more completely and more wholeheartedly than I ever did before. . . . That’s the only way to pay back part of that vast debt, to live up to and try to fulfill that tremendous obligation." Alfred Hornik, Sunday, December 2, 1945 to his family, on his continuing duty to others for surviving WW II. | |||
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Like most things in life the absolute black and white answer is not possible. There are all kinds of variations on .223 chambers. .223 Wylde for example does fine with 5.56 ammo. And lots of guns especially ones originally designed for 7.62x51 don't have safety issues but do have potential operational issues with commercial ammo. To the example above heavy (200g) and hot .308 ammo may be pretty stressful to the gas system on an M1A (like break op rods). “So in war, the way is to avoid what is strong, and strike at what is weak.” | |||
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