".410 or 12MM" and "One Piece Barrel" are marks used by Harrington and Richardson, 1877 to 1985. Diamond Arms was a trade name used by Shapleigh Hardware of St Louis. Your gun probably dates to sometime between the two World Wars.
remove barrel and serial # will be stamped on top of receiver on left
It was made in 1964.
Louis Diamond was born in 1902.
Louis Diamond died in 1999.
Diamond Arms was a trade name used by Shapleigh Hardware Co of St Louis from the late 1800s to about 1950. The guns were made by G. B. Crandall, Harrington & Richardson, Hopkins & Allen Arms, J. Stevens Arms Co, and probably a few others. A 410 single shot is most likely a Stevens product. If that statement about one piece barrel actually says "barrel and lug forged in one piece" it is a Stevens. If it says "barrel and lug forged in one" (exactly the same except no "piece") it is by Iver Johnson Arms and Cycle Works.
Some models of Diamond Arms were made by the Crescent Fire Arms Company for the Shapleigh Hardware Company of St, Louis, Mo. between 1982 and about 1922.
What type of info do you need? The gun is a Sweet 16 made in 1968. It has a flat knob pistol grip and is the last year Browning had the St. Louis address on the barrel. They changed to Morgan Utah in 1969.
An LR mark stamped inside a ring means that it was manufactured by a jeweler named Louis Rousselet. Louis Rousselet was from France and created jewelry for over 50 years.
Contact the Browning service desk at the link below.
Diamond Arms Company and Nitro King are both trade name used by the Shapleigh Hardware Company of St. Louis, Missouri. Some of the guns were imported from various Belgian sources, but they were also made by W.H.Davenport Firearms Co (1890's - ), Iver Johnson Arms & Cycle Works (early 1900's - ), J. Stevens Arms (before 1942), and Savage Arms. If there is an oval with ELG* stamped on the barrel or action, it is from Belgium, but being a 410 makes that unlikely. That also eliminates Davenport as the maker.
1837
This is a standard weight 16ga auto 5. It was made in 1962. The barrel should read: Browning Arms Company St. Louis Mo. & Montreal P.Q. If the barrel only reads St Louis and not Montreal, then the barrel is not original to the gun when it was sold.