Changes bolts to be made from materials with density 600 (equal to wood). This makes them lighter, and less able to penetrate armor. The [SHOOT_MAXVEL] values for bows and crossbows are also adjusted to 833, which should allow steel plate armor to block projectiles ~90% of the time and iron ~30% of the time. Other normal armors will hardly ever block projectiles, and spoilerish armors will block ~100% of the time. With vanilla DF34.11 values no armor ever blocks projectiles at all. This reduction of projectile mass and velocity does not seem to significantly decrease damage to unarmored targets. Blowdarts have not been modified in this version, and will likely penetrate armor 100% of the time. For more details of armor penetration by projectiles, see http://www.bay12forums.com/smf/index.php?topic=116151.0.

Usage:
Copy the contents of this folder to the root of your dwarf fortress directory (backing up is recommended). This will overwrite the following files in /raw/objects:
-entity_default: adds to [ENTITY:MOUNTAIN] (dwarves)
[PERMITTED_REACTION:MAKE_BOLTS_COPPER]
[PERMITTED_REACTION:MAKE_BOLTS_BRONZE]
[PERMITTED_REACTION:MAKE_BOLTS_BISMUTH_BRONZE]
[PERMITTED_REACTION:MAKE_BOLTS_IRON]
[PERMITTED_REACTION:MAKE_BOLTS_STEEL]
[PERMITTED_REACTION:MAKE_BOLTS_SILVER]
[PERMITTED_REACTION:MAKE_BOLTS_ADAMANTINE]
-inorganic metal: remove at [ITEM_AMMO] tags from normal metals.
-item_ammo: increase contact areas of bolts and arrows from 2 to 10.
-item_weapon: decrease [SHOOT_MAXVEL] for bows and crossbows from 1000 to 833.

Adds:
-inorganic_tipped_metal (light metals)
-rections_tipped_bolts (reactions to make bolts in dwarf mode)

Results:
All bolts and arrows in adventure mode should be "metal tipped", and have mass of 0.09 each (~2 kg per stack of 25).
In dwarf mode, you can make these bolts at the Craftsdwarf's workshop (not the forge). Reactions will also show up in the forge, but will not work as you cannot get bars of the light metals.

Adjustments:
You can change the values of [SHOOT_MAXVEL] for crossbows and bows in /raw/objects/item_weapon.txt if you want to make projectiles more or less able to penetrate armor. The bolts have a mass of 0.09, so their momentum will be SHOOT_MAXVEL*0.09 (which results in momentum=75 for the default SHOOT_MAXVEL=833). The plots in this post show the approximate protection offered by different armors at different bolt momenta. Momentum 45 should give about 50% deflection for copper and bronze armors, 60 for 50% deflection off iron, 110 for 50% deflection off steel, and 180 for 50% deflection off candy. I chose 75 as you get intermediate levels of deflection for both iron and steel, but that doesn't mean it's the best choice, so adjust to whatever you think is appropriate.

Testing:
The included spreadsheet "Mod_Ammo_Testing_V833" has results of testing these modded bolts in the arena. In each test, 1152 arena dwarves (modded to be uniform and not feel pain - see armor testing thread indicated above) were given breastplates, helms, greaves, 2 gauntlets, 2 low boots, and the indicated number of mail shirts. They were placed in 1 tile cells separated from shooters by a single fortification. The shooters were Great marksdwarves/archers and had crossbows and 100 bolts each. Hits, deflections, etc, were only recorded before the target dwarves first fell down, as armor is penetrated much more easily if the target is on the ground.