What is the rule regarding shotgun slug sizes?

The correct answer highlights an important aspect of shotgun shell compatibility. When it comes to shotgun slug sizes, it is critical to understand that while you can decrease the length of the shells you use, increasing the length can lead to safety and functionality issues.

Shotgun shells come in standardized lengths, such as 2 ¾ inches, 3 inches, and 3 ½ inches. If you use a shorter shell in a shotgun designed for longer shells, it will generally work without issues, but the reverse is not true. Using a longer shell in a shotgun chambered for a shorter one can lead to malfunction, chambering issues, or even catastrophic failure if the firearm is fired with an incompatible size.

Therefore, the key rule is that you should only go down in length when selecting slug sizes for a shotgun to ensure safety and proper functioning.