U.S.A., U.S. Flaming Shell Seal

U.S. Ammunition Seals, Image by StuE, Found by Paul O.
Found at Lavenham.

5 seals were found at this location each with U.S. on one side and a grenade with a burning fuse on the other. There is considerable variability between the seals in the size and detail of the markings - the U.S. can be in raised or sunken lettering and the 'grenade' sometimes has a neck between the body and the flames.
Rusty wire attachments are evident.

Lead seal with U.S. on one side and a flaming grenade on the other. Rusty wire attachments are evident.

See US metal ammo boxes with this marking on them. "The “flaming bomb” symbol of the Army Ordnance Corps was present on most WWII ammunition boxes."

See U.S. Army Ordnance Corps, branch insignia.

From Encyclopedia of United States Army Insignia and Uniforms By William K. Emerson. "The grenade device has been traced back as far as 1704 ... It was not until after ... 1851, that the historic insignia became used primarily by the Ordnance Department."

Ian T. located the following information - ORDNANCE DEPARTMENT LEAD SEAL HAND PRESS – RARE EARLY TO MID 20TH CENTURY INSPECTOR’S TOOL - MC Pheeters Antique Militaria "this United Seal Company hand operated Hot Press Tool was used for clinching lead security seals that were placed on packing crates and containers to prevent tampering and theft. Each of the jaws is fitted with an emblem discs to emboss the lead disc on the seal - one having 'U.S.' and the other has the Flaming Bomb insignia of the U.S. Army Ordnance Department." See link for images.