What can impact a shotgun's effectiveness apart from its design?

The effectiveness of a shotgun is significantly influenced by the training of the user. This encompasses various aspects such as familiarity with the firearm, understanding of its operation, knowledge of proper shooting techniques, and the ability to engage targets effectively. A well-trained individual is more likely to utilize the shotgun's capabilities to their fullest potential, ensuring precision and accuracy when firing.

Factors like legal ownership status may dictate the ability to possess and use a shotgun but do not directly influence its operational effectiveness. Brand reputation can provide insights into quality and reliability but does not guarantee proficient use. The color of the shotgun, while it may have aesthetic appeal or considerations for camouflage, does not affect the firearm's fundamental performance or effectiveness in practical situations. Hence, user training stands out as the most critical factor among the choices provided.