Might be the nicest French guild gun I've ever seen. Those marks could even be the retailers, which would further muddy the waters.
I really like shouldering sub 6 lb 12s, but, thats where the love ends. Hard on me, and hard to hit anything. I think Mike McCintosh opined that a 28 should weigh 6 lbs and he might have been right. My 6lb 4oz Tobin 16, loaded with Eley VIPs sure lets me know when it has gone off.

Best,
Ted