What caliber or smaller qualifies as small arms?

The correct answer identifies that small arms are generally classified as firearms smaller than .50 caliber. In this particular context, it's essential to recognize that small arms typically include handguns, rifles, and shotguns that are designed to be individually operated and require no crew for their operation.

Among the options given, .50 inch is the threshold caliber starting point for what is commonly recognized as the upper limit of small arms. Therefore, calibers that are .50 inch or smaller are considered small arms. A caliber of .60 inch exceeds that threshold, thereby falling outside the standard definition of small arms. This classification is crucial for identifying the appropriate usage, training, and regulations surrounding various types of firearms in military contexts, as smaller calibers allow for different tactical scenarios and applications compared to larger caliber weapons.

Thus, the caliber classification indicates that any caliber larger than .50 inch is not considered a small arm, making .60 inch an inappropriate choice as an acceptable caliber for small arms.