No apologies needed. You asked some terrific questions!
The primary difference between a rifle and a shotgun (they are both long guns) is in the bore, the inside of the barrel of a gun. A rifle, as with a handgun, is comprised of a bore that has rifling. Rifling is the spiral grooves cut into the bore, and it causes the shell to rotate in a spiral pattern. The significance being that the rifling increases pressure, distance, and accuracy. A rifle is usually shot at a ground level target. The bore of a rifle is designed with thick walls to withstand high pressure.
The bore of a shotgun, on the other hand, has thinner walls and is smooth, the only exception being shotguns made to fire a slug. In those fairly rare cases, the shotgun may have rifling. But most often, a shotgun features a thinner walled barrel without rifling to the bore, and is used to shoot moving objects in the air. The lack of riffling allows for less friction, less pressure, and thinner walls.
A handgun (pistol or revolver) also has a thicker walled but short barrel. Handguns have rifling also.
Handloading or reloading is the loading of firearm cartridges or shotgun shells by assembling the individual components oneself, rather than purchasing completely assembled, factory-loaded ammunition. The device used in this process is called a reloader.
Reloader Buying Guide While handloading and reloading are terms used interchangeably by everyone I've ever known familiar with the activity, to be very technical, handloading is the more general term, as some enthusiasts choose to load new cases or shells. New cases or shells are usually ready for loading. A casing that has already been fired requires preparation before reloading, such as the removal of expended primers.
Why would someone handload a gun? While I personally do not handload, some reasons that some people give are economy (for those who shoot regularly), commercial ammo shortage, performance/accuracy, the ability to underload for a beginner or for someone who is afraid of the recoil. Example, if a Mom or Dad wants to teach their daughter or son about guns, gun safety, and say introduce them to target shooting, but don't necessarily want to invest in a beginner gun, she or he can underload the gun so there's less recoil.
Potential Forensic Evidence
Hand guns (pistols and revolvers), rifles, and shotguns can all receive and discharge reloaded ammunition. Sometimes the distinctive markings left on a casing can be linked to a reloader. But it is more complicated than linking an unreloaded casing because multiple marks are left. See
A Quick Determination Method of Reloaded Pistol Cases by Observational Studies: A Precaution for Forensic Crime Scene Investigation
Absolutely, an overloaded gun or underloaded one, for that matter, can injure or kill.
Why Guns Blow Up Part III: Overloading and Underloading Ammo | Gun Explosion
I hope that is helpful. And don't ever apologize for asking questions.
