Thinking about buying an upper but it has no markings? How do i identify it?

[MADxBRAPPER]

I am thinking about Buying a 20" RRA upper with a wilson ss barrel 1:8 twist and i do not know what it is chambered in but was told it can shoot both .223 and 5.56 safely which makes me think its chambered in 5.56 or .223 wylde. All this info i have been told buy the seller. There are no markings on the barrel that say what its chambered for and there is nothing on the receiver that says RRA i have been told. I have pics but they are not great and i havent see it in person.

It looks like the upper in this pic, the bottom ss barreled one.

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=267

I have found on the net that you have to take the barrel out and there should be a 3 digit code on top of the breach. Any info on this will be appreciated. This is being sold by a trusted member of this board and was also bought from another trusted member of the board awhile back so i am sure its all on the up and up but i am driving down to San Diago today and would like to know what to look for to confirm it is what everyone says it is. -MxB

[Noobert]

AFAIK, most manufacturer's uppers are not marked except by the forge mark. I also think all RRA's are .223 wylde chambered

[MADxBRAPPER]

Thats pretty much what i have found as well....i am curious about the three digit code though....here it was i have found for the three digit code key:


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
205 =Chrome-lined light-weight R4, 1:7
206 =Stainless CAR
208 =16" varmint
210 =moly Mid
212 =Chrome-lined Mid
215 =Stainless Mid
218 =18" varmint
219 =Chrome-lined light-weight R4, 1:9
220 =moly Std (rifle)
221 =Chrome-lined Std (rifle)
222 =Stainless NM(rifle)
223 =Stainless NM (rifle), unthreaded
226 =20" varmint
228 =24" varmint (1:8)
229 =24" varmint (1:12)

There may be "S" & "C" after the numbers. The "S" is for stainless and the "C" is for chrome-lined.

Does RRA always use wilson barrels?