Tranqs needed not correct, is it just me?

[Zamirathe]

I have a Mastercraft Longneck that is 636.7% damage. I put this into the tool and it said I needed 4 tranq darts to take down the level 20 bronto. I shot it with 4 tranqs and it stopped about 1500 shy of it's final torpor (checked with Omnicular). It ended up taking 6 darts to bring him down. Is there something I have missed? I have checked all the settings and everything else works.

Note: This is on a modded unofficial server I run for my family on our LAN. This occurs with all weapons I have tried that are above 100%, so it isn't just a longneck issue and on all dinos so far that requires more than 1 shot.