5.56 NATO vs .223 Remington - What's the Difference?

Is say most modern recievers can handle both regardless of caliber stamped on it.
I shot plenty of 556 from my 223 mini
 
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FatCatsDad said:
Is say most modern recievers can handle both regardless of caliber stamped on it.
I shot plenty of 556 from my 223 mini[/QU



When I used to have a mini I used to shoot anything out of it . I shot military stuff out of it I used to get in the US and commercial stuff also . to me 556 and 223 were the same thing . never gave it a second thought . as long as it went bang and made a hole in the groundhog that's all that mattered to this guy . memories . that's all were going to have soon.
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rajczak_kashka said:
I beg to differ...but carry on
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Just for clarity, 7.62 NATO is fine in any 308 Win, 308 Win should be safe in most 7.62 NATO rifles, but some 308 Win loads can damage the gas system of the M-14 and possibly some other Battle Rifles.

I'm sure Ian pointed out that the only real world difference between 223 Rem and 5.56X45 is in the chamber, namely the throat.
 
randyhub said:
Thanks I will pay attention to the bolt lift. Is the heavy bolt lift on your Savage a concern of possible breach failure.
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Heavy bolt lift is a pressure sign. In the case of the Savage, I suspected (5.56 fired from that .223 chamber has) inadequate headspace. So after that day I didn't do it again.
 
redshooter said:
I'm sure Ian pointed out that the only real world difference between 223 Rem and 5.56X45 is in the chamber, namely the throat.
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Yeah, he was talking about very slight dimensional differences at the front of the case, plus the depth of leade engagement with the slightly longer bullet placement in one, which together can, in some chambers make for a bit of a bump in pressure. But he was quite dismissive regarding potential damage to a gun, let alone harm to the shooter, outside of very rare cases of mostly ancient rifles.
 
I know 223 Wylde is the middle ground compromise that was designed to shoot either (and shoot it well, the dimensions lend themselves well to good accuracy) - is there an equivalent for 7.62x51 / 308?
 
Sniffer said:
I know 223 Wylde is the middle ground compromise that was designed to shoot either (and shoot it well, the dimensions lend themselves well to good accuracy) - is there an equivalent for 7.62x51 / 308?
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308 and 7.62 NATO have identical chambers, it's the gas system in M-14 and possibly other semi-auto rifles that is the problem. Anyone that reloads for the M-14 will tell you, bullet weight below 180 gr, and a powder burn rate in the IMR 4895 range. If you don't limit it in that regard you will damage the gas system over time.
 
redshooter said:
308 and 7.62 NATO have identical chambers, it's the gas system in M-14 and possibly other semi-auto rifles that is the problem. Anyone that reloads for the M-14 will tell you, bullet weight below 180 gr, and a powder burn rate in the IMR 4895 range. If you don't limit it in that regard you will damage the gas system over time.
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So the chamber on a 7.62x51 and 308 are the same? Identical in all dimensions (including throat / freebore)?

From memory that is the difference between 223 & 5.56 - 5.56 has a longer throat. With this in mind I imagine the potential issue of using 5.56 in a 223 chamber would be if the round was long enough to be jammed into the rifling (due to the shorter throat) as that would cause a pressure spike when fired.

In my mind it would take a combination of the following things before there could be an issue:

1) 5.56 in 223 chamber with shorter throat
2) 5.56 is loaded on the hotter end of the spectrum
3) OAL of the 5.56 round is relatively long so it is jammed into the rifling when chambered (which would cause a pressure spike when fired)

Am I missing anything?
 
Milspec 7.62 has thicker cartridge walls and therefor less power volume than .308 - so former tend to have less pressure than latter. Weigh the brass or take a calliper to them. 7.62 also has a marginally longer headspace like 1/1000th of an inch if memory serves.
 
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