5.56 ammo in a .223 ar15 (my sig m400 enhanced)

[mackwage]

I recently purchased my first ar15. I went with the Sig M400 Enhanced.

Anyway, the specs on the site noted it was chambered for .223. I started reading about 5.56 and .223 and found SAAMI said it was unsafe to fire 5.56 in a .223 rifle. I also found a couple of sites that said some commercial .223 ar15's will allow you to fire 5.56 safely.

Anyway, when taking my rifle apart for its cleaning, I noticed that both the upper and lower were stamped with "5.56 nato".

So with that stamp, I would assume it can fire 5.56 but I DID buy the .223 version.. hoping someone could help shed a little light on it so I can be sure and safe. Thanks!

 

[aaron580]

Its safe. Sig M400 is designed for 5.56 primarily.

 

[03A3]

Its safe. Sig M400 is designed for 5.56 primarily.

I've never seen a Sig 400, 556 ect that wasn't chambered for 5.56 though there may be some.
What's stamped on your barrel is what matters.

 

[mackwage]

Thanks for the info. I was confused because sites like Gander Mountain listed it as .223.

Sig Sauer M400 Centerfire Rifle - Gander Mountain

 

[giovani]

What the chamber is cut to will be stamped on the barrel by the manufacture, and thats all that matters.

 

[223 Gunner]

If the barrel is stamped 5.56, then you can safely shoot both.

 

[03A3]

I think some places like Gander Mountain list guns with something like .223 instead of 5.56 because there will be some prospective customers who are not familiar with 5.56, but they've all heard of .223

 

[mackwage]

Thanks for all of the wonderful information!

 

[Jeremy1066]

Stamped "5.56" = safe for 5.56 or .223

 

[Regionnus Rattis]

I've never seen a Sig 400, 556 ect that wasn't chambered for 5.56 though there may be some.
What's stamped on your barrel is what matters.

I've a Sig M400 SRP...but I agree with this. I've not heard of an M400 chambered in .223. Go according to your rifle specs...not a web site.

 

[djhuckle]

Thanks for the info. I was confused because sites like Gander Mountain listed it as .223.

Sig Sauer M400 Centerfire Rifle - Gander Mountain

A lot of people will incorrectly interchange the two, so you must be diligent when researching to get the manufacturer's spec not something in an advertisement. Like the others have said, 5.56 takes both, but there is also the .223 Wylde out there.

.223 Wylde - Wikipedia, the free encyclopedia

 

[efpeter]

+1 for the barrel markings. That is what matters.

A Gander Mountain AD is not really a reliable source of factual information....

 

[HemiWes]

Should be stamped 5.56 out near the end of your barrel. Mine is