There are two types of leaks: Valve leaks and seal leaks.
If gas is coming out the barrel, that is a valve leak and a lot harder to fix.
If gas is coming out the seal around the tip of the cartridge, that is a seal leak.
This is how to fix seal leaks.
Step 1: Materials
- The leaky gun in question
- Full cartridge
- Teflon plumbers tape, available at any hardware store that is worth shopping at.
- Silicone spray lubricant or Paintball marker oil. Do not use any other type of oil, it will freeze and damage the seal even more.