All of forward momentum and speed crossbow bolt has, it received from the crossbow string that pushed it forward. That means that, if bolt was moving faster than sound, the string had to do it first. Which means that crossbow string broke the sound barrier - along with the accompanying deafening sonic boom and shockwave - something like 6-12" from the shooter's face :D
You know the loud noise that's made by a gun? That's mostly the sonic boom of the bullet. You know that "pop" a whip makes, also a sonic boom.
What you are forgetting is that only a very small portion of the potential energy of things that do create sonic booms goes into the boom. Most of the energy goes into useful work (flying through the air), and heat. If your x-bow had enough potential energy to create a dangerous sonic boom, the boom would be the least of your problems, just shooting the thing would at the very least rip your arm right off.
Seriously though most of this is pure sillyness and theorycraft at its extreme and is not really meant for actual gameplay. Only by using pathfinder physics is this even remotely possible.
When I created this thread I did it as a place to compile a bunch of crossbow material 3 years ago. Hopefully we can update the material with new options as they become available.
Yeah, so crossbows are a little more viable since you can now use almost any bow feat with crossbows via the crossbow mastery feat. However, it is so feat intensive that it is rarely used. I suppose you could find a way to get a vestigial arm to reload two identical crossbows with crossbow mastery and dual wield them. With vivisectionist, you could deal wield with free reloading, and get sneak attack damage... Does that sound right to you? It does to me.
I am working on a double crossbow build that uses the crossbowman fighter archetype, but its main goal is to get enlarge person and gravity bow on a double crossbow before using a readied action to vital strike. It stacks up well, denying target dex to AC, adding dex to damage, not to mention deadly aim. I think the main advantage is the number of dice you can abuse. The full combo with the spells and greater vital strike is doing... 24d6 of just weapon dice damage.
I'm wondering if anyone has any ideas about how I can trick out my cleric's crossbow.
He's a cleric of Abadar (or a re-skinned version thereof), with domains as Travel and either Metal or Defense.
I was thinking going up to Crossbow Mastery and using a Heavy Crossbow. Alternatively, I could free up some feats and stick with a light crossbow, choosing Rapid Reload and a few others to keep the weapon fairly decent. But heavy has such a visceral appeal! (Either way, I'll be doing other things, not just shooting all the time.)
I'll definitely pick up a Guided crossbow at some point. I was also considering Create Reliquary Arms & Shields to make my crossbow a holy symbol, which just seems cool.
Apart from that, I'm really wondering about crafting or buying special bolts. I don't see a lot of great ammo options out there and am looking for suggestions. If I want to make my own magic bolts, would that even be possible - since a lot of the relevant spells would be on the sorcerer/wizard list, I assume?
It depends allot on what your DM will allow. My suggestion for special bolts would be to make batches of bane bolts of different races. As a cleric can cast summon monster this is a easy one to make.