Greeting and Salutations We are currently working on a project I would like to share with the community and hope to acquire more information on. I am hoping that someone can shed some light on the nomenclature stamped into the rings. They are as follows: (my notes) 3.7cm SK C / 30 U (37mm U boat Gun) L.C / 39 (U Boat Mount) (the rest of the markings are what I need to verify) Eagle and Swastika M (on left side) B (on right side) U (below) One gun follows this arrangement with 1601. It has 57847 above the Swastika /1601 It also has 639 (6 may be an 8) on top of the ring. The other gun follows the MBU and Swastika with a 1590 Has 57847 and 516 on top of the ring. I was told that the MB is the area of operation or group and that the following # is the catalogue #. Any way to substantiate this or to follow the catalogue #? Any way to identify the # on top of the ring? Both of these are Boats, but neither boat seems likely. Both of the #s on the tops of the rings and catolage #s were hand stamped after the gun had been factory marked. These guns were put into service for the Spanish navy on the Dedalo (USS Cabot Independence Class Aircraft Carrier) post war and then the ship was scraped back in the US after leaving Spanish service. The guns would have been in Spanish inventory post war. Since the guns were largely considered obsolete they may have been on boats turned over prior or during the war by the Germans. I am hoping someone has records or contacts in reference to the markings or history of these guns. Here is a link to some pics of one of the guns. http://www.ordnance.com/37mmuboatdeckgun.html Here is a link to Video of us firing one of the guns. I would think this is the only one in the world that is functioning. I hope I am wrong. Hope you enjoy and Thank You in advance. http://www.ordnance.com/uboat-deck-gun.html We are working on quite a few unusual items and I will post some material from time to time to share.