I may have to revise my numbers as they seem to be incorrect. An Electrum limbed crossbow (electrum limb, paper binding, cobalt tough rod, bowstring) with Many tipped bolts (feather fletching, wood shaft) can one-shot everything I've tested it on so far, including Fallen Knights and Wither Cats from EnderIO, even at a range where the damage should be significantly lower than their hit points. As a result, I will be doing more comprehensive testing to come up with what is actually going on here.
Also, an addendum to crossbows which I like: Right click and hold to reload. Letting go loads the bolt. Then right click again to fire, but if you hold down the right click, it will draw back immediately. This makes it, effectively, bolt-action, and a nice compromise. I feel this is more balanced against bows, simply in reverse. Once you load your crossbow, your shot goes off immediately, then has time to reload, instead of drawing back to fire and firing. Either way, you've got a delay between shots, however the crossbow fires immediately whereas the bow is generally faster (all other things being equal) and has no reload time after the shot.
I will be doing more testing and release the findings once I am confident of their accuracy.