Yeah, the chaingunners are tricky, but there are a few options. I'll write those below in case you don't want to be spoiled. I'm so glad I didn't adjust the difficulty, because I have to actually lose on purpose in order to die, so a bullet have been avoided there. Spirit form is not very controllable at the moment, so it's something you can at best redirect or try to keep the speed moderate. Thanks for playing!
Kicking the flying enemy into them will explode and instakill (unfortunately it's not very consistent at the moment), you can spirit form through, or rush to the wall in front then melee when its safe, or just have a dakka-off until they drown in their own shells.