Is your propane bottle at its last legs/almost empty?
I noticed that the pressure drastically drops toward the bottom of the bottle and there might not be enough pressure in the bottle to fully fill the mag. I had the same problem with my G23F mag.
As well, temperature of both the mag and the propane bottle might have something to do with it. I had a bottle of propane in the "cold room" of my house. I filled the mag in the cold, then took it into the house. After about 15 minutes or so i tried to fire the gun. The gas had expanded/warmed in the mag to the point that i had a hard time releasing the gas using my finger on the valve never mid the fact that the hammer with upgraded spring could not release the valve.
|