Original Item. Only One Available. This is an excellent original U.S. 3-inch Stokes-type trench mortar Practice Shell, Mk I, fitted with an inert Trench Mortar Fuze, Mk VI and retaining much of its dark-blue practice finish and white identification stenciling. The complete assembly measures approximately 16 1/2 inches long and survives in unusually strong condition for an early trench-mortar projectile, with scattered oxidation spotting and a heavily dented brass-colored fuze nose being the principal condition issues.

This example is fully inert and demilitarized, with a hollow projectile body and inert fuze components. It contains no live explosive filling or functional energetic charge. Not Available for Export.

The 3-inch Stokes mortar was developed during WWI and became the standard British light trench mortar, while the United States subsequently adopted the weapon and produced its own ammunition and fuze components for the system. Imperial War Museums documents the British 3-inch Stokes light trench mortar as a First World War weapon, while U.S. War Department technical regulations provide detailed instructions for American 3-inch trench-mortar ammunition.

Unlike later fin-stabilized mortar ammunition, the Stokes projectile was essentially a cylindrical steel bomb without tail fins. U.S. technical instructions specifically note that the 3-inch mortar was smoothbore, imparting no spin to the shell, and that the projectile was consequently unstable in flight and could strike the ground in virtually any orientation.

The mortar measures roughly 16 ½” long, with the body having been painted blue. The body is stamped:

3” S…
SHELL …
LOT NO-13
S.A.A. 10.1… 24
PRACTICE

The word PRACTICE, combined with the dark-blue finish, corresponds directly with U.S. War Department identification standards for the Practice Shell, Mk I. The technical manual specifies that practice shells were externally painted dark blue and stenciled in white with the caliber, shell type, mark, ammunition lot, loading plant, and loading date.

The practice projectile itself was intended to duplicate the ballistic weight of the service high-explosive shell without carrying its normal explosive filling. Period U.S. instructions describe the Practice Shell, Mk I as being filled with approximately 2.15 pounds of sand to reproduce the weight and range of the high-explosive projectile. When originally fired in service, a special practice booster could produce a visible white puff at impact to mark the strike. This surviving example has since been completely deactivated and is now hollow.

Fitted to the nose is an American Trench Mortar Fuze, Mk VI. The Mk VI is what period U.S. documentation called an “Always” type percussion fuze, meaning that it was designed to function upon impact regardless of the attitude of the unstable shell. The War Department specifically states that it could function if the projectile struck nose first, base first, or sideways. The term all-ways acting is therefore appropriate modern descriptive terminology, although the period manual itself uses “Always” type and percussion fuze.

The fuze retains its original pull ring and can still be unscrewed from the projectile for inspection. Its brass-colored upper cone or nose has suffered substantial denting, but the remainder of the exterior assembly remains well preserved. The fuze is entirely inert.

The Mk VI incorporated a particularly interesting safety arrangement. A safety pin passed through the setback pellet and prevented movement before firing. Once the round was dropped into the mortar and accelerated by the propelling charge, setback released the safety fork. The fork was initially prevented from leaving the fuze by the wall of the mortar tube itself and was only expelled after the projectile cleared the muzzle. This left the percussion mechanism capable of functioning on subsequent impact. The original War Department manual illustrates this mechanism in section and identifies the setback pellet, safety fork, striker, springs, primer, and related internal components.

This safety arrangement was directly related to the unusual flight characteristics of the Stokes projectile. Because the shell had neither spin stabilization nor tail fins, there was no assurance that its nose would be pointing toward the target at impact. The Mk VI therefore used an inertia-sensitive mechanism capable of responding to impact from several directions rather than depending upon a conventional nose-only impact action.

Overall condition is excellent for an early Stokes trench-mortar projectile. Much of the blue practice finish and important white stenciling remain visible, while scattered oxidation spotting is present across all pieces. The brass-colored nose of the fuze is heavily dented, but the fuze remains removable and retains its pull ring. Unlike the heavily excavated or fragmentary examples frequently encountered, this shell remains a substantially complete and readily identifiable display example.

The combination of the dark-blue Practice Shell finish, surviving U.S. stenciling, Mk VI all-ways percussion fuze, original pull ring, and complete cylindrical Stokes configuration makes this an especially instructive example of early American trench-mortar ammunition. Its design reflects the transitional nature of WWI mortar technology, before the fin-stabilized projectiles that became standard in later military mortar systems.