I was about to say "I don't see why he doesn't take more inspiration from long proven ballistics like bullets" but I realized his projectiles don't behave like bullets do. His seem to go in a straight line only stopping if something to tough gets in the way or it reaches it's max range, doing most of it's damage by virtue of being fucking huge. A bullet does most of it's damage by shattering/deforming and then tumbling inside the target. I'm not sure if he could get his to do that or not or if he'd even need to.
Yeah, spin is added to bullets for stability, not penetration. It is not a drill.
That said, he probably could make it drill-shaped if he wanted to (but can he do that without using too many primitives and raising the level needed?), in which case spinning it
would help it dig.
I am more curious why he is so fixated on the "solid shape manipulation" aspect of his magic. It is
Life Magic, meaning it should be the most versatile magic affinity and thus have tons of extra tools in its arsenal. Just taking a page from kazuma's book, he could have it cover the floor in water and freeze it to make black ice (or even more slippery. and maybe even a thin layer of water left ontop?). And if he layers the appliance-charging magics, he might be able to electrocute enemies. Dirt removal might be modified into a flesh removal spell? And so on.