Anyone knows, please, the meaning of this shield-shaped stamp?



It comes from the barrel flats of a nice 12 ga. W.W. Greener Far Killer hammergun, ordered from Italy and made in 1884. I asked to Graham Greener (very kind and collaborative as always!) but the stamp is unknown even to him.

This is very first photo I put on internet, so I hope it will go allright...

TIA,
Maxm