Is this a real Luger or a knock off? (It looks too good.)

[Sealgair]

Originally Posted by Edward Tinker

as Geo said, they put new east german barrels on them, thus why it is pristine.

That makes a lot of sense. As I look at it, even the exterior finish of the barrel is different than that of the pistol (a lot shiner).

I think the matching crown N on the barrel led me to think it was an original stamp from the manufacturer.

I am curious, though, what gave it away? Was there a marking that stood out? Or is it just the knowledge of the experts?