Hidden Bow attributes?

I heard that there may be possible bow bonuses that are applied to some bows. I know what all the firing rates and ranges are for them. But for some bows, like the Horn bow where the range isn't quite as good as the long bow and the refire rate as good as the short bow, I heard that there might be a possible armor piercing bonus applied. Has anyone been able to confirm this, and if so, what is it? I am curious to know if there is ever a reason I should go with a Horn bow, or if I am better off having a long bow for long range shots, and a short bow for in close battles. Thanks.

For each bow they've got a few things to consider, rate of fire, range and arc or arrow speed, plus a few bows have an inbuild but unstated armor penetration value, i think horn bows do, but i cant remember what else.

Horn bows/shadow bows/ivory bows have built in armor penetration +10%. This probably is to compensate for their slow refire rate.