My bottle is empty....when I have it filled is it better to put the bottle in the freezer and get is ice, frozen cold? also my bottle is showing 400psi, is it better to empty the bottle all the way since its just air or should I leave whats in there in when I have it filled?

 

If it is air you can let it out. Try to find someone who uses a pump to refill nitrous. Then you don't have to go through the bottle freezing process.

 

Its "just air"???? No, its vapor phase nitrous, and there is no reason to throw it away.

 

I have done them frozen and not. It seems like the cooler they are the better the fill but maybe it's just me.

 

When I don't freeze my bottle, I get just under 10 lbs in the tank. But The last time I had it in the freezer and had it filled they squeezed 10.4 lbs into it.