these both work but you can hear air escaping when you tighten the cartridge. they are automatics and might be best for collectibles as they are rare.  Part of the requirements for listing in this category state that sellers include the disclaimer below. Please copy and paste the following text into your item description:

This listing complies with eBay’s air gun guidelines found here and I will only sell and ship air guns to buyers in jurisdictions where permitted by applicable laws 
http://pages.ebay.com/help/policies/firearms-weapons-knives.html