Alright. Here's photographic evidence.
Quiver's contents, page 1:
Page 2:
That's a total of 450 bolts in a single quiver.
Here's how it works: In order for the marksdwarf to store the bolts in his quiver upon being marked on duty (this works even if you put him back to off duty immediately, as the act of putting him on duty cancels the practice job), a couple things must be true:
1: There must be a valid stockpile that will accept the bolts he's carrying.
2: Said stockpile must not be full, counting a square as full if a stack has already been tasked to be moved to it.
3: Strangely, if the bolts were taken from a valid bolt stockpile this stockpile
must not still be valid and non-full by the time the practice job is canceled.
Testing procedure:
- I had several stacks of bone and wood bolts, one of which was on a one-tile stockpile.
- Marksman was set to off-duty.
- As soon as I saw him pick up a stack, I paused the game.
- - While paused, I designated an ammo stockpile larger than the number of dwarves I currently had item hauling enabled for.
- - - (If you have one dwarf, a 1x1 will suffice. I tried 1x1 with no item haulers, 1x4 and larger with 3 item haulers, and both worked. 1x3 with 3 item haulers did NOT. I conclude that items are tasked to the stockpile before the marksdwarf has a chance to decide to stow the bolts or not, and since the stockpile is then full, point 2 fails and he drops them.)
- - From the military menu, selected his squad and put him on duty, than off again.
- Unpaused, and he put the bolts in his quiver.
- When he picked up the stack that was already in a stockpile, I tried two things to test point 3:
- - I did NOT designate a new stockpile, but merely put him on and off duty. He dropped the bolts instead of stowing them.
- - After pausing, I deleted the stockpile the bolts came from and designated a new one as above. He happily stored the bolts.
Incidentally, there's another way to get it to work, and it's how I did originally it in Ceilingmansion: Have SO MANY FINISHED GOODS (as in, I put stone crafts on repeat for years on end) and stray goblin clothing lying around that, through sheer force of numbers, there's no WAY the few stacks of practice bolts are going to be chosen to be moved to stockpiles instead of the couple thousand obsidian mugs. Thus point 3, the sticky one, automatically succeeds.
Well, I'm excited, I dunno about you.
ETA: Thanks to bhamv and Quatch for calling this to my attention and testing it, respectively.
You can get a marksman to store bolts without setting him on anf off duty by simply making the archery target impossible to use, either because the room is set so the firing direction is wrong (e.g. put it against a wall and tell him to shoot from the wall's direction) or, my favorite, make the room too small. However, the 3 points regarding stockpiles above still have to be true. Basically, if you have no item haulers or way, way too many non-bolt items for them to haul, this will save you micromanagement time. However, if this is NOT the case and bolts are being hauled to stockpiles before your marksdwarf gets his hands on them, you will STILL have to micromanage just as much, that and it's a little harder because you have a smaller window of time to interfere; if he gets to the bolts before you have time to realize he's trying to practice and screw with the stockpiles, he'll immediately drop them, instead of giving the extra time it takes for him to get to the archery target. However, there's zero chance that you'll miss it and he'll waste the bolts, so your call.
Thanks also to Khanddak for making me test having multiple ammo stockpiles. Turns out, if the stockpile the bolts were taken from is still valid when the practice job is cancelled, he'll drop the bolts, even if there's another valid stockpile that's closer.