What a great Idea I've been looking to inject Co2 for a little while but not to sure how to approach it. I can't belive this idea, I've worked in the fire industry for a while and have at least 30 co2s in my garage. Well 28 now, to are coming into the house.
Just one thing to everybody who is going to do this be very careful when you remove the horn If the pin is still in the co2 handle then thats okay but whatever you do. DO NOT PRESS THE HANDLE WITH THE HORN REMOVED the pressure inside will knock your arm back so hard and thats if you can hold onto it as well as throwing the co2 cylinder 25yards backwards. They are very dangerous so be careful. Still a fantastic Idea.
Excellent advice cybortech, i wouldn't even attempt to do anything to the cylinder until the regulator is in position and secured tightly, only then would i remove the safety pin and secure the handle in the open position, this is a pressurised cylinder so should be treated with due respect, always make sure the regulator is attached to the cylinder first of all, once you take this precaution it is as safe as using a normal CO2 cylinder.
@ mantis147.......no, that regulator will not work, its the wrong type, yours has a male thread, you need the opposite, a female thread is whats needed as pictured below.
This is my regulator which has a female thread, this is the type of fitting you want
This one here below is very similar to your own, this is off a beer keg regulator, but unfortunatly it will not work, as its a male thread as well.
The regulators in the 2 links that i gave in my reply to RYO will both work, there are others available that will also work but they are a lot more expensive, and tbh i dont see the point in spending big bucks on a regulator, the cheaper ones will do the same job and it will more than likely be hidden from view anyway.