Been sitting here running around it for a half hour shooting into it's mouth whenever it surfaces, slashing at it's side whenever it lunges and misses, killing all the little worms.  There;s no real feedback letting me know if I'm even making progress towards killing it.  Starting to get frustrated.  Is there some mechanic I'm missing that would help me take this down any faster?
 
Now just watch me take it down 2 minutes after I post this.  :\

you have to break his face mask first

It is broken.  I've been shooting his dongole for 30 minutes.

YEWTEWBZ IT!

if its broken shoot it in the juicy insides then :D thats the mouth by the way >_>

What works for me is if I saves my dashes and run right in front of it and just keep dashing if he gets near

" What works for me is if I saves my dashes and run right in front of it and just keep dashing if he gets near "

If you're doing everything correctly and he hasn't died in a half hour, it is majorly bugged.  Once you've broken off his muzzle you just keep shooting him in the mouth until the prompt comes up and that's it.

Yeah that fight took a really long time, long enough my hands were getting sore from holding down the camera lock.  Keep at it, you will get through it.

Welp.  I saved my dashes and used them whenever he got close.  Then the framerate got choppy, kept doing the same thing for another minute or so, then I fell through the ground.  I'm currently plummeting about a mile or two below the environment.  
 
All that time wasted.

What I did was rush up his side after doing a u-turn when he charged me, then slash the shit out of his face plate.  Then he was easy pickins' once his face plate broke.  (Shoot it in the face a ton)  It probably took me 10 minutes after his face plate broke which took 10 or so, so it can be a long fight.

Yeah.  I was shooting him square in the face for a good, long time.  Guess the encounter bugged out for me.

Just did this again.  Took 5 minutes.  Guess the first encounter was just bugged for me.