Spanish shotgun markings

Here is what we have so far.

Unknown elements and meanings.
Nautilus in center?
620 K 2 ( Kcs?) possibly proof pressure?
3 on the web between the 2 barrels ?
B with the star or * on top ?
P 1322 Gs  Barrel weight in grams?

There also appears to be a 18,2 mark on the barrels that I suspect may be choke, as well as a small highly worn oval with a couple illegible of characters that may be the makers mark and a W or M possibly a P in a diamond on the left barrel. Yet to confirm what it is.

Also not sure as to the meaning of the O on the receiver flats. If it is  year code it would correspond with 1944 and this is in conflict with L = 1939 on the barrel.