Final answer:
If a 20 gauge shotshell is loaded into a 12 gauge shotgun, it would not fit properly.
Step-by-step explanation:
If you were to load a 20 gauge shotshell into a 12 gauge shotgun, it would not fit properly. This is because the gauge measurement refers to the diameter of the shotgun bore. A 20 gauge shotgun has a smaller diameter than a 12 gauge shotgun. So, the 20 gauge shotshell would be too small to fit securely in the 12 gauge shotgun chamber.
It is important to only use the correct gauge ammunition for a shotgun to ensure the safety and proper functioning of the firearm. Firing the wrong gauge ammunition can cause serious damage to the firearm and potentially injure the shooter or others.