Bag charges

Principally because of the difficulty in handling very large cartridges cases, and espe-cially in disposing of empties, the cartridge case in large-caliber guns is replaced by a powder charge assembled in a silk bag. The gas checking is accomplished by the mush-room and pads on the breach plug, and the primer is fired by a lock attached to the breech plug.

Bags used for bag charges are manufactured of pure silk without the admixture of any material other than sizing for the yarn. Heavy cloth is used for the body of the bags; light cloth, for the ignition ends. The ignition end of each bag consists of a red-colored quilted pocket containing an ignition charge of black powder.

Loading: Bag charges are either "dump" or "stack" loaded. In dump loading, the pow-der, after weighing, is dumped lossely into the bag, and the bag is then rolled and tightly laced to form a compact unit. For lager-caliber guns, stacked bags have almost comple-tely replaced dump-loaded bags. Stacking places the powder grains on end in layers, to that a tight, compact, and uniform charge is obtained. Stacking results in greater ease for loading crews, a smaller charge bundle, a consistently uniform charge, and a longer life for the bag, as there is less change for the sharp edges of the powder grains to cut the cloth of the bag. The arrangement of rows and number of grains in stacked charges is so fixed that the finished section will be the proper length according to Bureau of Ord-nance standards. This arrangment differs with each bag index and is found by actually loading a test charge.

Nomenclature: As the term "Service Charge" has resulted in confusion, the new standard nomenclature is as follows:

Full Charge - for use with H.C. or A.P. projectiles at full velocity.

Reduced charge - for use with A.P., target, or H.C. projectiles at reduced velocities.

Special - any charge other than those listed above.

The following types of bag charges may still be found:

Service - for use with A.P. or H.C. projectiles at full velocity.

Target - for use with target projectiles.

High-Capacity - for use with H.C. projectiles.

Charges suitable for use with either H.C. or target projectiles have hitherto been known as "H.C. Special" charges.