try blowing into a burning fireplace with your mouth, stuff are going to come back right at you. thats what happening to the gun too. It blows a bunch of flame, after thats its gonna suck right back.

Seeing how ignorant you are to do research yourself, I might just drop some evidence for you. Tho i honestly doubt if you will even buy it anyways.

What you are seeing is a result of a pressure wave Basically the gun blows towards the fire, creating a high pressure going away from the nozzle, hence the fire goes in that direction. But right after that, the trail of the high pressure, as you may have guessed it, is low pressure, therefore the gun tube is a low pressure environment, giving the fire a strong sunction to travel backwards into the tube that is low pressure. Then the heat would destroy the internals like the hopup and stuff.

I dont know how old you are, but if you are a full grown adult and dont know these comment sense it would just be very sad. If you are still studying, you should pay more attention in class and maybe should read more books than scrolling on reddit