How well do these nice cheap Fusion 20ga slugs shoot ?
Unfortunately the only way to find out if they will shoot for you is to shoot them.
With a rifled barrel you Don't want to use slugs., they are for smoth bore barrels.
You want to use sabots, they are for rifled barrels.
The term "slug" refers to the projectile.
The term "sabot" refers to the plastic piece that holds the projectile.
There are plenty of full bore (non sabot) diameter slugs out there that are ment to be used with rifled barrels.