There is armor penetration, but you can ignore it (5%), at most it will be 30 or 40 damage when people have 1-2k..
(used q10bow because my armor are bad

)
Without armor:
https://gfycat.com/AcrobaticThinBlackbuck((50 * sqrt(11,5/10) + (60 * sqrt(235/10)) * 72/100 = 248
With armor:
https://gfycat.com/FrighteningSickIcelandicsheepdog((50 * sqrt(11,5/10) + (60 * sqrt(235/10)) * 68/100 = 234.41
234.41 * 0,05 = 11
same with metal arrow:
https://gfycat.com/AdolescentKaleidoscopicHoneybadger((50 * sqrt(11,5/10) + (70 * sqrt(235/10)) * 58/100 = 231.23 (aim is a double, not a int, but i only display the first 2 digits on my client that why there is a little dif here)
https://gfycat.com/ExaltedBossyFantail((50 * sqrt(11,5/10) + (70 * sqrt(235/10)) * 58/100 = 231.23
231.23 * 0.05 = 11.56 (~12)