The rifling grooves impart the torque that makes the spin for better trajectory of a bullet.

Would the same be convenient to have for a projectile in outer space; -no air, no gravity- ?  What if the projectile is spherical ?

What would the grooves grab onto in the almost vacuum of space?

The spin imparts directional stability.
Same reason a spinning top stays upright and doesn't fall over.
It has nothing to do with air, and would give a space-going rocket more problems than it would alleviate.

8 hours ago, Externet said:

The rifling grooves impart the torque that makes the spin for better trajectory of a bullet.

Would the same be convenient to have for a projectile in outer space; -no air, no gravity- ?  What if the projectile is spherical ?

If there's no air to cause the path to deviate, what would be the gain?

Thanks, gentlemen.

I sense the effects of two actions  in your comments.

The rifling in the barrel producing the initial torque, and the tiny grooves 'imprinted' on the bullet surface that interact with air during flight.  Do both take part in the gyroscopic effect ?  Are the markings on the bullet helical or straight ?

6 minutes ago, Externet said:

Thanks, gentlemen.

I sense the effects of two actions  in your comments.

The rifling in the barrel producing the initial torque, and the tiny grooves 'imprinted' on the bullet surface that interact with air during flight.  Do both take part in the gyroscopic effect ?  Are the markings on the bullet helical or straight ?

I don't think the grooves are a major player in this during flight. It's the angular momentum.

The bullet grooves are angled, because the rifling is helical

The 'rifling' imparts the spin to the bullet in the barrel. That's where the bullet gains all its momentum ( linear and angular ).
The spinning bullet's angular momentum resists changes to momentum along other axis.
This gyroscopic effect will keep it from tumbling end over end ( the other axis ), due to destabilizing forces,  and keep its nose pointing forward.

These destabilizing forces are more prevalent in air, but even in space, rockets are subject to external forces,  or imbalances in the thrust line caused by CG shifts ( a spinning unbalanced rocket will experience precession of its thrust line instead of larger and larger deviation ).

Edited July 1, 20196 yr by MigL