minies in smoothbore

[GunnyGene]

Like many other things today, they’re designed to sell, not work.

Though I, too, heard they were supposed to pass through a choke easier. I wonder why the groves have a “twist” to them if that was the only reason.

Straight lands and grooves on the slug make it more difficult for the slug to get thru a choke. A twist gives the lead a place to move to as it passes thru the choke.

 

[Britsmoothy]

There is the theory that the compressed air in front of the slug on leaving the muzzle could induce some very slow twist.
There are other designs to try and achieve that too