How can i tell if my bore/barrel is 5.56 or .223?

[Chadzillaa]

It is not stamped on the barrel. It is however, 1/9 twist and crome lined. Is there any way to tell if it is 5.56 or .223? Thanks

[Thomas M-4]

It is not stamped on the barrel. It is however, 1/9 twist and crome lined. Is there any way to tell if it is 5.56 or .223? Thanks

http://www.m-guns.com/tools.php

Ned makes gages and reamers.
Most likely if you got a 1/9 twist its going to be a .223 style chamber.

[Iraqgunz]

Chad,

Who makes the barrel? It is almost a sure bet that if it is 1/9" from the typical manufacturers DPMS, Oly Arms, Bushmaster (older ones), it is more than likely .223. If you have a Noveske, BCM, Colt, LMT, Sabre (I am sure there are others) then it is more than likely 5.56.

Not sure about Stag Arms or Spike's.


It is not stamped on the barrel. It is however, 1/9 twist and crome lined. Is there any way to tell if it is 5.56 or .223? Thanks

[Chadzillaa]

Thanks for the replies, guys. Its a Model 1 sales barrel stamped with M1S. Its been a great upper...I've put about 3000 rounds of various brass through it, and some wolf, without a single malfunction. It eats up everything and is surprisingly accurate. Maybe giving them a call about the chamber wouldnt hurt.

[Fyrhazzrd]

It looks like it could go either way judging from their website. It looks as though when you are ordering your barrel you have the option of .223 or 5.56 chamber. So yes I would say you would have to contact them to know for sure.

[Robb Jensen]

If the Ned Christiansen 5.56mm NATO chamber checker falls easily out of a chrome lined barrel then it's probably a 5.56mm NATO chamber.

If it sticks on a stainless barrels chamber you might have a .223 Wylde, Noveske MATCH or a SAM-R chamber or similar. Most of the time you'll see these types of chambers in stainless barrels.
In non chrome lined carbon steel barrels there are all kinds of chambers out there.

[ST911]

Good advice in here.

Gauge it with Ned's gauge to see if it's a nominal dim able to handle 5.56. Ream, to go one better and be certain it's GTG.