I thought there is a 3 digit number letters that tell if the barrel is chrome lined or not but could not find it in a asearch. Anybody known?

Mine has the #204 under the gas tube by the delta ring. Steve at RRA confirmed mine for me. Hope this helps.....Trapfan.

you sould be able to look threw the upper and see a little chrome on the barrel. You can also remove the flash hidder and see it.

http://www.ar15.com/forums/topic.html?b=2&f=38&t=149779

You can also take cold blue on a Q-Tip and dab a little in the bore. If the cold blue "sticks", then the barrel is NOT chrome-lined.

The top sticky in the RRA section in 'Industry'  defines it.  Steve has the following:

"Applicable "codes" for 223 barrels:

Old Codes:
Three characters side by side over the chamber.
First Character: N or W...N for NATO chamber or W for Wylde
Second Character: 8 or 9...8 for 1:8 twist and 9 for 1:9 twist.
Third Character: A, S, or C...A for moly (chrome -moly Alloy), S for Stainless, and C for Chrome-lined alloy.

New Codes:
The actual base part number from our parts system/catalog, located over the chamber. These are the most common. Unless indicated otherwise, all stainless barrels are 1:8 twist and all moly barrels (chrome-lined or not)are 1:9. All 16" moly barrels have a NATO chamber, while the 20" moly and all stainless barrels have a Wylde chamber.

200 =moly CAR
200CL =Chrome-lined CAR
202 =moly R4
204 =Chrome-lined R4
206 =Stainless CAR
208 =16" varmint
210 =moly Mid
212 =Chrome-lined Mid
215 =Stainless Mid
218 =18" varmint
220 =moly Std (rifle)
222 =Stainless NM(rifle)
223 =Stainless NM (rifle), unthreaded
226 =20" varmint
228 =24" varmint (1:8)
229 =24" varmint (1:12)

Steve/RRA"

a simple look down the chamber should work

Thanks for the link, its was a 212 mid chrome line barrel