Do Rifled Slugs Actually Spin?
Russ Chastain 12.20.17
If you know anything at all about shotgun slugs, you probably know what a rifled slug is, also known as a Foster-type slug. Generally, these are hollow-base lead slugs with angled grooves around the perimeter. The angled grooves are the so-called rifling on a “rifled” slug.
These slugs predate rifled shotgun barrels, and were designed to be fired through smoothbore shotgun barrels. Does the “rifling” on the slug actually make it spin as it travels through the barrel, or not?
Let’s find out.
They fire a few of these slugs, which do rotate in the direction of the “rifling,” though not very much. But how does that compare with slugs that don’t have any rifling on them? To answer that, they got hold of some smooth-sided slugs to try.
The first shot, which the narrator said “performed well” without spinning for stabilization, actually turns sideways just before hitting the target — a condition known as keyholing, which indicates unstable flight. So I have to disagree with them on that.
The bottom line is that yes, rifled slugs to indeed spin in flight, due to rotation imparted by the “rifling” on the exterior of the projectile.