YES - i KNOW THIS IS A GRAVE DIG.....
But thought I might fill in a little detail.
Bruce [I guess you were with Tarra' gun shop??]
I purchased one of these "Vietnam rescue" Ithica '37's back when we were allowed to have them.
Best $200 I ever spent!!
In the short time I owned her, she did sterling service on feral pigs, cats, emus, ducks, rabbits and the occasional roo.
Mine had a "bantam" length buttstock - possibly cut down to suit underfed [and undersized] ARVN conscripts?
The barrel had similar markings as described in the post above - cylinder bore, with over-stamping designating full choke.
I was told by a retired Vietnam era USA military armourer that originally these shotguns were fed practically nothing but 00buck, until lead shot was deemed unethical, and then steel fletchette shells were adopted.
Unfortunately, the fletchettes spread faster than the 00buck, so the barrels were swaged down to full choke, giving a tighter pattern which was very close to that of the 00buck out of a cylinder bore barrel.
I still cant work out how 40 odd fletchettes would be any more ethical than 9 lumps of 00buck!!
I still miss my sweet little '37........damn that JWH.