New (to me) AR... How to tell if 5.56?

[TENGRAM]

There is no stamp on the barrel indicating whether it is 5.56 or not. How else can I figure it out?

[slowyellow]

Have you looked under the handguard?

[ThreeFingerPete]

Look under the handguard. What else do you think it might be?

[BradM]

Did you steal it or something?

[Downs]

Just by looking at it I'm guessing 5.56/.223.

[Nash B.]

Look under the handguard. What else do you think it might be?

I'm guessing he's asking how to tell if it's .223 or 5.56.

[YALE]

Odds are, it's a 5.56 chamber. Don't be skeered!

[brandon01rt]

Seperate the upper/lower and drop a round in the chamber.

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[Craizie]

Seperate the upper/lower and drop a round in the chamber.

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a .223 and 5.56 will load in a gun chambered for one or the other. doesnt mean you should do it though.

[TENGRAM]

Have you looked under the handguard?

I haven't removed the rail but I have a pretty clear line of sight through it; didn't see any markings there. Is it possible that it would be under the gas block/front sight base?

Did you steal it or something?

Bought it from a friend of the original owner and he didn't have any details on the upper.

Seperate the upper/lower and drop a round in the chamber.

Not sure how that'll help since .223 and 5.56 are externally identical.

A little research has indicated that the difference between the two versions is the throat, or "leade", space... the 5.56 chambered barrel throat is almost twice the length of that of the .223. Trouble is I'm not real clear on what is considered the throat.

[BradM]

Bought it from a friend of the original owner and he didn't have any details on the upper.

.

So, he stole it?

[Fatass]

Pull the hg, I'm sure it is marked somehow, somewhere. If not, rebarrel it if it makes you feel safe. Aim has several spikes barrels pretty cheap with a 5.56 chamber.

[brandon01rt]

I thought he wasn't questioning .223 vs 5.56 more like 5.56 vs 300 blk or 6.8...
Didn't read

[GAP]

Just don't shoot 5.56.

[CJ]

has to be stamped somewhere on that barrel. Or some firing/proofing marks.