I have had mutliple failures to fire, but this was due to an incorrect headspace issue on the CVA Kodiak Mag. I have had a partial ignition in a CVA Kodiak Mag using 777 pellets that I believe to be weather / care related and therefore relevant here.

Loaded the gun and went for a morning hunt in Southern Michigan during late December many years ago. The tempuratures were negative numbers and I hunted as long as I could stand it. I was so cold I brought the gun into the house and put it in the corner with the barrell poiting up as I tried to feel my fingers again (I am sure you guys can relate). Took the gun out that night for an evening hunt and had a doe come in at 20 yards broadside. Leveled the gun, pulled the trigger and received a "pop" then fireworks come out of the end of the barrell. I was able to reload and nail the doe.

I believe the condensation formed in the cold barrell causing moisture to get into the powder. The power of the primer & some ignition was enough to move the load out of the barrell. IMO, the "fireworks" was powder igniting as the pellets fell apart during inconsistent ignition.

Since then I simply keep the gun in its case in the garage and do not bring it in the house. I have not had any issues since.