It is interesting to compare the design of these, not really "driving bands" but grooves into the solid mono shank of the bullet.

Below is the GS Custom design where there are driving bands above the shank.

The spent projectile image of the GS Custom projectile shows the rifling only contracted the driving bands, not the shank for this projectile meaning less friction and wear and pressure on the barrel from the mono bullet.

A difference in design.