I don't want to be rude, but I think you have some incorrect data at some point that leads to error. These numbers don't line up / aren't correct. I'm guessing you're RoF assumptions are wrong maybe?
Example: The Volt has a 12.0 rounds per second RoF, and does 16 damage. It takes 13 shots to kill a non-fortified non-low-profile target at 100 shields. We don't count the first shot's cooldown in TTK, so that leads to a 1s TTK on 100 shields targets.
Edit: I'm looking into what info we can share out publicly, so hopefully the wonderful folks that do this data work have less guess work to do! No promises, but I'm looking into it!