I have a 16'' M4 profile barrell that my buddy says is a RRA.  How can I tell?  It is not stamped behind the flash hider like my colt.  I have not taken the handguards off to see if there are any markings there.  Does RRA mark theirs.  I can tell it is chrome lined because of the chamber end has got the silver/white dusting around the bore?

Thanks

I thought RRA used Wilson barrels.

Wilson does make most barrels.
Mine I got from Pete-in-NH, all chrome lined, R4 SOCOM (heavy) and no marks whatsoever.
Love them!
You can tell if it is chrome lined if you can see the chrome at the muzzel end & a dry wipe moves smoothly through the barrel. Most barrel steel is all the same 4140 chrome molly. Bushy & Colt use 4150 steel, a better grade than most. Chambers are M16 or Wylde - not sure which on what with RRA - although their web does say the SS are Wylde.

The RRA Markings are usually on the barrel by the spot where the gas tube runs into the upper receiver.  Hope this helps.

Thanks, I found out today that the markings for a RRA barrell are under the handguards just before the gas tube enters the reciever.  I found a table on the general discussion board with the description of what would be stamped on the barrell.  Mine says N for nato chamber, then 9 for 1 in 9 twist, and C for a chrome bore.  Example N9C.

If anyone needs to look at it is under the post "RRA 16'' barrell?'' in the ar discussion board.