Which item is crucial for maintaining firearm accuracy?

The quality of ammunition used is essential for maintaining firearm accuracy because it directly influences the consistency and reliability of each shot fired. High-quality ammunition typically has tighter tolerances in manufacturing, which results in better uniformity in the bullet's weight, dimensions, and powder charge. Such uniformity leads to more predictable ballistic performance, improving accuracy and precision when shooting.

When using inferior or inconsistent ammunition, variability can occur, affecting trajectory and grouping on target. Therefore, selecting high-quality ammunition tailored to the specific firearm and intended purpose results in more accurate shooting outcomes.

Other factors like the type of gun, cleaning frequency, and even shooting glasses can play a role in the overall shooting experience, but they do not have as direct an impact on the fundamental accuracy of the shots as the quality of the ammunition does.