Complex sentence: The longrifle is an early example of a firearm utilizing rifling, or the spiral grooves in the bore of the weapon giving the projectile, commonly a round lead ball, a spinning motion assisting with stabilization in flight trajectory.
Split into simpler sentences: The longrifle is an early example of firearm utilizing rifling, or the spiral grooves in the bore. This gave the projectile, commonly a round lead ball at the time, a spiraling motion, increasing stability in flight trajectory.