Why are we so stingy ?

For most barrels we have only four or six rifling grooves.

When Marlin gave us more grooves, they shallowed their depth keeping the stingy mindset.

We want lots of deep grooves.

And why only a constant number of rifling grooves in a given barrel ?

Start with six rifling grooves near the chamber. Add another rifling groove about a quarter of the way. And yet another groove as we approach the muzzle.

Let's not be so stingy.