subcaliber gun

subcaliber gun

[¦səb′kal·ə·bər ′gən]
(ordnance)
A gun mounted on the outside and above the tube of a larger gun; it is used in practice firing of subcaliber ammunition, in connection with aiming drills with the larger gun.
References in periodicals archive ?
Fortunately, there are still some subcaliber guns and conversion unite made to fill what is now a niche market.