Dwarfs are magic. They can dig out (say) 500 tiles and the best of the miners produce nearly 500 stones that can then be dumped into one of those dug-out squares while leaving it perfectly passable, while the worst of them (or a tag-team of inexperienced miners, to avoid anyone gaining too much ability) can reduce it down to a mere handful, with no problems even of dust.
But apart from that, I think of Dwarves as being implicitly magic, not explicit. They hate the whole hand-wavy, chanting, etc, but the way that the best of them bash away at an iron bar and create an intricate quality goblet may not be entirely due to the more mundane skills.
A metal bolt that does massive damage may be due to a particularly practiced method of serrating the bolt, it could be some intricate mechanism forged within it's shaft that springs out additional barbs once it has struck and penetrated with the target (with armour-piercing bodkin head, where necessary), or it could be an imbued magic.
But you wouldn't catch them actually invoking spirits or inscribing mystic runes on ammo or weapons. Ordinary dwarf runes, maybe, like a bolt with something that translates to "A present from Boatmurdered" or an edged weapon with "Have a nslice day!".
Which does not preclude ammo that has somehow been engineered to contain an ice, magma, or miasma compartment that... somehow... releases an inconveniently large/rapid amount of cold, heat or disease upon the target. But it wouldn't be magic...
(An analogy from 40K, or at least as I understand it from frequent discussions with a friend who is into it more than I am: Orcs are psychic, but they just don't know they are. When they paint a war kart red "to make it go faster", it does...)