Thread: 223 or 5.56

Originally Posted by timattalon

because we all know the internet is never wrong......

We ARE on the internet, so if that's your approach, why would you take anyones advice for/against .223/5.56x45 compatibility on this forum over the many articles google can find?

Wikipedia isn't a perfect source either, but is a good starting point, as it is meant to have footnotes, citing the original sources of the information. Keep reading until you are satisfied you have found your answer. Or don't - just have a go and let us know how you get on.

https://en.wikipedia.org/wiki/.223_R...C3.9745mm_NATO

Short answer is that it (safety) depends on the chamber of any particular rifle.

Originally Posted by stretch

We ARE on the internet, so if that's your approach, why would you take anyones advice for/against .223/5.56x45 compatibility on this forum over the many articles google can find?

Wikipedia isn't a perfect source either, but is a good starting point, as it is meant to have footnotes, citing the original sources of the information. Keep reading until you are satisfied you have found your answer. Or don't - just have a go and let us know how you get on.

https://en.wikipedia.org/wiki/.223_R...C3.9745mm_NATO

Short answer is that it (safety) depends on the chamber of any particular rifle.

That does somewhat make sense. I see where its coming from now. There still seems to be some debate as to what is safe and what is not but it makes more sense than some of the earlier explanations. It does clearly state that both are dimensionally the same and that one is effectively a "hotter" load designed for a longer space before engaging rifling.

5.56 vs .223 - What You Know May Be Wrong - LuckyGunner.com Labs

So what about this then?

If you had read the link you would realise that it is fine to fire 223 in 5.56 so perfectly acceptable to sell and market 223ammo as suitable for both and mark a 5.56 chamber as 5.56 and 223 but not the other way around this is the point.

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Originally Posted by veitnamcam

If you had read the link you would realise that it is fine to fire 223 in 5.56 so perfectly acceptable to sell and market 223ammo as suitable for both and mark a 5.56 chamber as 5.56 and 223 but not the other way around this is the point.

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That would work if it was marked 5.56 (223) but it chambered in .223 and also takes the 5.56x45. If I am reading that properly that is the other way around.

Originally Posted by timattalon

That would work if it was marked 5.56 (223) but it chambered in .223 and also takes the 5.56x45. If I am reading that properly that is the other way around.

How do you know which it is chambered in?
From a manufactures point of veiw it would be safest to ream everything to 5.56 lead no matter what is stamped on the barrel.

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Originally Posted by veitnamcam

How do you know which it is chambered in?
From a manufactures point of veiw it would be safest to ream everything to 5.56 lead no matter what is stamped on the barrel.

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That would make sense, It could be a similar situation to shotguns where you can use a 3" magnum in a shotgun chambered for 3.5" but you cannot do the other way around. But I would have thought they would have labelled the barrel 5.56 (223 if that was the case. But as long as I know I can use both it becomes moot what they have done. In this situation I know the manufacturer also makes larger calibres and apart from the chamber and diameter of the bore there is no other external changes to the rifles action etc so the action and barrel are capable of handling much larger calibres and pressures so perhaps for them it is a non issue.

5.56x45 is just a dimension, and could be used to describe any variation of 223 REM or 5.56mm NATO ammo/chambers. E.g. a barrel marked 223 REM/5.56x45 will most likely just be 223 REM.

Well from what I can read, there is also a second pressure pulse (apparently) So the first is the pulse that overcomes the bullet's inertia to leave the case, the second is when the bullet touches the lands, hopefully we all know about this? Many testers and equipment dont measure this second one which maybe the key one for the 556/223 issue as its so highly strung. So simply the books I have from knowledgeable ppl prepared to write about it in a book (ie are legally then liable as opposed to some knowall on a forum with a name like "jacksmackhead" who's "never had an issue") say you have to check and if need be ream the chamber to make it safe in all conditions. Add in that an AR15 gets extremely dirty, more abused and hence and hotter than a bolt action (who does 30~60 round mag dumps from a 223 boltie? in a minute?) so yeah sure. ie compare apples with apples.

My stance is to be safe and err on the side of caution, especially as there seems to be no real gain for most people.

"I am not going to even hazard a guess at how much higher" Some of the tests I have read suggest an AR15, dirty, on a hot day and abused (so hot) can exceed the bolt's test pressure done when new. Now this test pressure is done 1 or 2 times and never meant to be repeated and not 30 rounds (or more) from a mag dump.

On the other hand of course we dont see lots of pictures of f****ed AR's and ppl missing bits of hand / face.

There is a good kindle book series by Patrick Sweeney Gunsmithing the AR15 vol1 and vol2 and The Gun Digest book of the AR15, vol1 to 4, 6 books in all, worth reading IMHO.