In firearms, rifling
is the helical groove pattern that is machined into the internal (bore) surface of a gun's barrel
, for the purpose of exerting torque
and thus imparting a spin to a projectile around its longitudinal axis during shooting. This spin serves to gyroscopically stabilize the projectile by conservation of angular momentum
, improving its aerodynamic stability and accuracy over smoothbore designs.
This picture, taken in 2016, shows the conventional rifling of an Austro-Hungarian 90 mm (3.5 in) M75 cannon, manufactured in 1891, on display at Ljubljana Castle in Slovenia.Photograph cr: Petar Milošević