The reflection from the light makes it look stainless, but note this line in the description.

"Only a couple of light marks on the blueing. ".

The gun was advertised as blue, so if I was the seller I would have a problem with you backing out because of something you assumed. The fact that it may not be the greatest buy in the world is beside the point.
I'd say enjoy your new frame .
I'll bet it will serve you well.