On guns there is a groove through the barrel correct? If so then should I Rifle a pbc barrel for a ball berring or not for target practice.,

Yes, firearms typically have grooves within the barrel, which are part of a rifled barrel. These grooves help impart spin to the bullet as it travels down the barrel, improving accuracy and stability during flight. When it comes to using a PVC (polyvinyl chloride) barrel for target practice with ball bearings, rifling is not necessary and could actually complicate things. PVC is a common material used in air guns or spud guns, where the projectile (such as a ball bearing) is often not designed for conventional rifled barrels. Simply pushing a ball bearing through a smooth PVC barrel can provide adequate results for basic target practice. If you are experimenting with projectile physics or looking for maximum accuracy, you might consider other materials and designs that are better suited to the type of ammunition you intend to use. However, for basic target practice, a smooth PVC barrel should suffice and may be easier to design and construct. Always remember to prioritize safety in any project involving projectiles.