The largest caliber ammunition that we classify as "small arms" is?

The classification of small arms ammunition is based on its caliber, which refers to the diameter of the bore of the firearm. Typically, small arms are defined as any weapon that is easily portable and can be handled by an individual.

In the context of this question, caliber .50 is recognized as the largest caliber that still falls under the category of small arms. This classification is significant because it denotes the type of weapons and ammunition that are primarily used by infantry and in many military and law enforcement applications.

Caliber .50, often represented by the .50 BMG (Browning Machine Gun) cartridge, is widely used in both machine guns and sniper rifles, providing substantial firepower while remaining manageable enough for individual operational use.

While calibers .60 and .75 are indeed larger, they do not classify as small arms and are generally reserved for specialized applications or less portable systems, such as mounted or vehicle weapons. The .30 caliber also falls into the realm of small arms but is smaller than .50, making it less relevant in this context.

Thus, the classification as small arms is why caliber .50 is considered the largest caliber in this category.