Crossbow arms don't impede with the bolt at all, the bolt sits on top in a sort of groove. I was about to say, "well, DF crossbows are made of steel so surely the spring speed thingy is way faster than conventional crossbows" before realizing all crossbows had a set launch force thingy. (I know physics very particular definitions for terms like force and power, but my science is really rusty so they all just mean "oomph" for the purposes of this post)
So presumably, if the crossbow's arms are made of steel, they're made a lot thinner than they would be if they were wood. Dwarves are clever like that.
This brings me to my next point: just like Adamantine has some weird, non-real-world properties, as do Dwarf Crossbows: they launch with the same oomph regardless of how heavy the bolt was. I figure if we should be consistent, and fire our crazy tricked-out impossible metals from the crazy impossible crossbows. A DF crossbow firing a near-weightless bolt really would launch it at the speed of crazy, if not for imposed arbitrary speed cap.
...Which, now that I think about it, might be representative of the speed of the bow string.
Anyways, here are the crossbow's stats for reference:
[SHOOT_FORCE:1000] (Any idea how many Urists to a Newton?)
[SHOOT_MAXVEL:1000] (in what, Urists per frame?)
To the best of my knowledge, a higher shoot_force than what would allow the bolt to go at the max velocity doesn't give it any more oomph, right? so the max velocity is like the bowstring's speed. So I think what we need to figure out is, does a candy bolt a)hit the maximum velocity, and b)is that fast enough to offset the mass problem? Is there a fast enough to offset the problem?
Also - the idea about the slade core bolts is pretty brilliant.
Lastly, re: Mrhappyface on chain mail: Mail makes pretty terrible padding. I don't really know much about the science, but I know a heck of a lot about archaic armour. The point of mail is to keep the other guy's weapon from cutting you, but not to stop or even distribute much the force (read:oomph, not necessarily Force, I don't really know) of the blow. It was extremely common for people to get broken bones and various other internal trauma from hits even when wearing mail, without it breaking the skin at all. That's why underneath it, people wore thick leather/wool padding (also because it got really cold). Plate armour, on the other hand, stops the cutting and distributes the impact, but had the disadvantage of having to be made all in one piece, which was a lot more skill and tech-intensive (though less time-consuming) than making hundreds of little metal rings (which could be done by apprentices). It was also more difficult to repair for the same reason (rings could be swapped out without much trouble). Adamantine would make excellent mail armour because of how hard it would be to break, although it's high rigidity would be wasted (wouldn't make things worse, but wouldn't help much). In current dwarf fortress combat rules, I don't think wearing leather underneath your armour adds a lot, though. Thus the effectiveness of blunt weapons. Interestingly, from what I've read (based on Roman-level tech, anyways, things might have changed by the middle ages) it was virtually impossible to actually penetrate armour with a cutting or stabbing weapon back in the day without siege weaponry or certain kinds of axes. Soldiers were trained to go for the unprotected feet and neck (gross, I know) which is where most of the injuries we find on skeletons are, and in general armies with armour had absolutely enormous advantages over armies without (barring other concerns, like surprise, treachery, and ambush. see: Teutoburg forest.). So in that respect, Dwarf Fortress has it absolutely dead on. It's the first game/movie/book/anything I've seen actually get that right. I love this game.