Today while I was playing,I found out that I can change flamer into secondary.
when the "flame god mode"times up,quickly press "q" to change into your primary,then flamer become the secondary weapon,fast reload,endless flame......
I've tried it twice,all success.
Is this a bug or sth?

Its supposed to be that way.

You don;t have to switch primary adn secondary at all. When time's up, the timer and darkened screen goes away, but the flamer is still yours