Take a close look at the receiver cover. I do believe that it is stamped lightly with the <I> stamp which is a refurb stamp from the 5Th Grau Arsenal. I could be wrong, may need a better pic. But it looks to be there. Circled in the pic:
A closer pics of both sides of the buttstock would help as well. Sometimes the wood is stamped with a square with a / through it which is also a refurb mark. Also take a picture of the electropenciling of the gas tube serial the buttplate serial and the gas piston serial. The extractor claw serial will help as well. The numbers and letters should look the same if written by the same person. If they were pieces that were matched during refurb there will likely be differences between the lettering and numbering handwriting style. A clear pic of all those parts serial and include a clear pic of the rear sight leaf serial will help us compare. Not all refurbs were stamped with refurb stamps. If this one went through refurbishment I do believe it was a light one.
Otherwise it is a beauty no doubt about it.