This is pretty interesting…I certainly didn’t know when slugs were invented…makes sense, given the old “buck and ball” shot (well, not just old, you can still get it). Anyway, these are known as “Cut Slugs.” They’re a field expedient alternative shotgun slug. These munitions were used back before true slug munitions were available.

I’m not terribly sure why sometimes they just randomly open up with the rifles, unless it’s to contrast the effectiveness of the Cut Slug.