How many shots does it take to kills someone with a venator when someone’s shields have been taken off?

Hey I’m curious how many shots it takes to kill someone with no shields. I had an incident today where my friend cracked this guys shield right but my friend got downed I followed up with a few shots 2-3 (he ran) then another 3 shots after he pushed me and he wasn’t taking damage. Blood was spraying off him but he was somehow taking every shot I hit and downed me within a few seconds with a kettle I think it was.