Other arms (for example, spring, air or gas guns and pistols, truncheons), excluding those of heading 93.07. - Guns and pistols, spring or gas

In your application for an advance ruling, you suggested tariff classification number 9305.99.90.00. This tariff classification number is incorrect. The goods are used as a propellant for airsoft guns. The World Customs Organization's Explanatory Note to heading 93.04 states guns which compress gas into their barrel when the trigger is pulled to eject ammunition are classified in that heading....

Source: advance_ruling (8000006910)

04 covers other arms, including arms that operate by means of spring, air or gas, which are not classified in heading 93.01 to 93.03 or 93.07. Based on the characteristics of the product, it meets the description of the goods described in Explanatory Note (6) to heading 93.03. This Explanatory Note (EN) indicates that "Captive-bolt humane killers resemble pistols for firing blank cartridges....

Source: advance_ruling (C-2015-002615)