Mod.66 cartouche|General Discussions & Questions|Forum|Winchester Collector

I asked about this gun, Mod’66 s.r.c. ser#161665, before and just curious if any one has any thoughts on it. The cartouche is on the left side and top of the stock close to the butt plate. all I can make out on the circular cartouche is a crown over an  encircled cross in the centre , what I think is a unicorn to the right, the left side is gone, a bit of scroll work under the cross,  and the words COAST PROT—(very faint), on top ARMSPROTEC—-, on the bottom, around the outside. I’ve tried to get a decent picture but just can’t. The gun itself is in very good cond. with some finish left on it and a really good bore with decent rifleing. It sure would be nice to know something about it. P.S. The other curiosity is why would a military or commercial institution buy ’66,s when the far superior ’73 had already been available for a number of years at this point(1883).