User blog comment:Reikyu/Plot Armor Part 2/@comment-25477086-20150329040902

So if we assume the cap is somewhere between 77.8% and 80%, I guess next would be to find a closer value of what the cap would be.

For this I took a level 3 Taigei (armor unmodernized) and ran through 1-5 some more. I did this for armor values up to 25 (as Taigei leveled a lot) as I didn't want to go too high on armor else damage mitigation for non overkill hits would start to overlap with overkill hits. This provided plenty of data as even Head On would proc overkill damage for almost all hits.

If overkill damage caps at 30/39 then that's 76.9% damage

If overkill damage caps at 31/39 then that's 79.4% damage

This would be a good experiment to see if I can hit a value above 78%. I ran through 57 attempts of this just hoping that 31 would show up so that I could call it a day, but it didn't happen. As this is purely based on the whims of RNG, it doesn't rule out the possiblity that 31 could still show, but still important to take note of it's absence. Data below is sorted by overkill damage