From the search I just conducted this appears to be a bug, unless there is something rather obvious I've missed.
My crossbowdwarves are sparring in the barracks with their crossbows, gaining levels in Hammerdwarf as they go. This is occuring even with:
Enough free archery targets for all dwarves,
Enough bone bolts for practice,
Weapon settings for each of them set to 'Crossbow',
Squad lead by a Crossbowdwarf
A couple of them seem capable of doing the right thing. They have never sparred with their crossbows (evidenced by their lack of 'Hammerdwarf' skill).
But others simply ignore the targets, ignore the bolts (some are even CARRYING bone bolts with them as they spar!) and just refuse to do any crossbow training.
What's weird is that they all have successfully trained on the archery targets in the past. They all have 'Dabbling Marksdwarf' in their skills, and I saw them using it yesterday. Today, however, at least four of my seven crossbowdwarves prefer to club eachother over the head instead.
I've tried this in a squad, and in individual squads (i.e. squadless), and I've tried setting them to Unarmed until they drop their crossbows and then switching them back-- none of this helped. There are spare bone bolts available, there's no problems with the archery targets... I'm convinced this is a bug, basically.
They have no injuries.
Save file provided-- note that I use two minor mods: Molten Rocks (modifies rock temperatures) and Engravings (adds new preference/shape text). Also using Mayday's graphics set.
The only files modified are:
descriptor_shape_standard.txt
matgloss_stone_layer.txt
matgloss_stone_mineral.txt
I'll provide them along with the savefile.
Download
here.
Thanks