Subcaliber

Subcaliber is a term used to describe ammunition, projectiles, or devices that are smaller in diameter than the bore of the weapon they are used with. It is commonly encountered in discussions of artillery, armored vehicles, and firearms training, where a smaller-caliber device must be fired from a larger-bore system or used for practice at reduced cost and recoil.

In large-caliber guns, subcaliber ammunition typically employs a subcaliber projectile housed in a sabot. The sabot provides a proper fit in the bore and is discarded after leaving the muzzle, while the subcaliber penetrator continues toward the target. This arrangement enables realistic ballistic testing, reduced wear and expense, and investigation of penetrators or armor development. Armor-piercing fin-stabilized discarding sabot (APFSDS) rounds are among the best-known subcaliber applications, using a long, slender penetrator inside a sabot.

In training and testing contexts, subcaliber devices include inert or drill rounds and subcaliber adapters that allow practice with less recoil, lower cost, and fewer hazards than full-caliber live ammunition. Such systems support gunnery training, safety demonstrations, and performance evaluation without firing full-power rounds. Subcaliber training can also involve adapters or inserts that enable firing smaller projectiles through a larger weapon for instructional purposes.

Subcaliber concepts are not limited to traditional firearms; they appear in other fields where a smaller-diameter projectile is used within a larger bore for testing, demonstration, or training. The common thread across uses is the interaction between a smaller projectile and a larger weapon system, often facilitated by a sabot or adapter to ensure proper engagement with the bore.