Practice Bombs of WWII

© Jerry Penry


The M382A practice bomb was widely used during training missions over targets in isolated areas. It simulated a General Purpose bomb of the same size and weight. The color of this practice bomb was a powder blue color to quickly differentiate it was a live bomb. Construction was a light sheet metal forming a cylinder for the main portion with a square box tail fin assembly. At the base, or fin end of the cylinder, a spotting charge was inserted.

Typical stenciling on a M38A2 practice bomb.

One known type of spotting charge used with the M38A2 was the M3. The M3 spotting charge consisted of a 3.5-inch canister filled with black powder. The top of the canister was a cap holding the firing pin assembly. The firing pin consisted of a metal plunger (inertia weight) inside a 0.75-inch diameter housing that was 2.5 inches in length and threaded on the end inside the canister. The plunger had holes which lined up with holes on the housing. A thin piece of round metal with a raised nib on it was at the bottom of the housing. Approximately one quarter on an inch separated the bottom of the plunger from the firing pin. Below this firing pin was a blank 28-gauge shotgun shell pressed downward into a threaded cap that attached to the housing and to the canister cap. Upon a sudden and jarring impact, the steel plunger struck the thin metal firing pin which fired the 28-gauge shotgun shell inside the canister which was surrounded by the black powder.

The cap of the spotting charge canister with the housing holding the plunger, firing pin, and shotgun shell, typically shot upwards and away from the main portion of the bomb upon impact. The rest of the bomb smashed into the ground and a large puff of white smoke from the black powder charge marked the location of the impact in relation to the ground target. The M38A2 bomb filled with sand typically smashed itself into an unrecognizable accordion shape.

M3 Spotting Charge Canister

Red = Plunger (Inertia Weight)
Yellow = 28-gauge Shotgun Shell
Blue = Canister Cap & Firing Pin Housing

Recovered M3 Canister Cap from a Nebraska bombing range.
(Bent Firing Pin Housing)

Cleaned Canister Cap with Firing Pin Housing.
The right photo shows remains of 28-gauge shotgun shell primer.

The pieces making up the Canister Cap.
(Canister Cap, Lock Nuts, Washer, Threaded Housing, Plunger, Firing Pin, Threaded Cap with Shotgun Shell)

Canister Cap with a 28-gauge shotgun shell inserted.
28-gauge shell at right shown actual size.

Example of a M38A2 practice bomb after striking the ground. The canister cap is to the lower left.

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