smartbomb, your carbine maybe one of the original unissued ones.
Check to see if:
All the serial numbers are of the same font with no re stamps or electropencilled numbers (other then the gas cylinder, piston, underside of the rear sight, extractor). The original unissued condition carbines have that deep red shellac finish on the wood with a single set of serial numbers stamped into the butt, unblued crown on the barrel, bare metal on the leading edges of the body cover "fork" (from fitting), two tone body cover, no wear marks on the bottom of the bolt from either the disconnect or the locking shoulder, and were stored with that dark brown stain on the bayonet.
These refurbs have a brighter bayonet, blued muzzle crown, lighter coloured stocks frequently with re stamped numbers in the wood, some with minor stock repairs, a darker finish with signs of some handling and wear under the bluing, among other cues listed in curtton's sticky.
If it is one, don't strip the shellac or "oil" the stock or remove the finish off the bayonet. A refurb would be a suitable plinker, with this one maintained for it's original collector's value.