Text copied from TM-E 30-451, March 1945 :
"Hollow Ring Charges (Hohlringladung).
(1) Description: These charges, used principally for the destruction of gun barrels, contain TNT, in a thin annular metal casing which is slipped over the gun barrel and fired by a cap. There is an annular, hollow space of semi circular cross section on the inside of the ring, designed to increase the cutting effect. The fragmentation effect of these charges is negligible, which makes them suitable for use by raiding parties and patrols.
(2) Characteristics: Hollow ring charge for anti-tank and machinegun barrels: Weight: 2 pounds 11 ounces, Outside diameter: 7.1 inches, Inside diameter: .. inches, Width: 5.1 inches. Hollow ring charge for field guns: Weight: 7 pounds 1 ounce, Outside diameter: 10.4 inches, Inside diameter: 6.7 inches, Width: .. inches".
Photo © Joachim.