> With the Coleman canisters, I could hardly get any gas out of the canisters. Currently I'm using Primus canisters, because they're the only ones I can find of that size, and while screwing the stove on the canisters, there's always a point at which gas starts to escape from the canisters before the stove is completely screwed on.
Yeah, so much for the official rules ...
It all depends on the little brass rod which sticks out of the screw thread. This goes into the canister and pushes down on the valve to let gas out. In theory ... there is a defined length for this rod.
I have been measuring the amount of rod needed to reach the valve for a whole range of canisters. Sigh. There is at least 1 millimetre variation between them. It is even worse when you include the Campingaz and Powermax canisters in the lot. The different brand stoves turn out to have slightly different length rods, to match.
So what to do? For the Coleman canisters - you may have to screw the stove onto the canister just that little bit harder. I do NOT like doing this myself because that leads to wear on the thread on the stove (not on the canister) and ultimately the stove thread strips and then the stove won't work at all. That happened to me in France.
For the others, where the gas starts to come out a little early ... well, at least you have gas ... For these cases I screw the stove on gently until I sense that the rod has contacted the valve. Then I give it a quick half-turn, to get to the sealing point quickly.