Can you use 16 gauge nails in 18 gauge finishing gun?

No, you cannot use 16 gauge nails in an 18 gauge finishing gun. The two gauges refer to different sizes of nails, and an 18 gauge gun is designed specifically to work with 18 gauge nails. Using a larger gauge nail in a smaller gauge gun can lead to jams, damage to the tool, and unsafe conditions. Always use the appropriate gauge nails for your specific nail gun.