Are most people overestimating how many arrows would be lost in combat, given enough time to recover them afterwards as part of the ten minute post-combat rest? This blog has 50% attrition, Talysman has 33%. It doesn't look like too many arrows would be broken even shooting against armor (here) so the main source of loss would be sticking in the wound and being broken off, being trodden on in combat, or just disappearing into the distance. It may be useful to overestimate these occurrences, though, if only to have ammo supplies play a meaningful part in an adventure.
|Also topical for Valentine's Day.|
Here are a couple of ideas:
1. Track ammo supplies using toothpicks stuck in a piece of modeling clay, packing sponge, or styrofoam (personally I hate the sound of squeaking styrofoam so that's right out.) Pull your "arrows" out when you shoot them and turn them in if they break or are abandoned. Indicate special arrows (magic, silver, etc.) using marker on the tip.
2. Arrows, magic or otherwise, break immediately on a natural damage roll of 6; I also have a missile fumble that breaks the arrow. Otherwise, there is no need to have a fiddly "realistic" system or extra dice rolls to model what is ultimately just another aspect of logistics like food, water, and light source consumption. So, breakage and loss are abstracted after the combat; each archer loses 1 out of every 4 arrows shot, rolling d4 to see if there is any loss when a fraction of that is shot. If the party flees the battlefield, of course, losses are total. Magic arrows can be exempted from this due to superior construction, although they may be picked up by intelligent foes.
3. Arrow heads can be loosened to become unusable after any hit (including a hit that would connect with an unarmored target even if it missed due to armor) and 3/4 unrecoverable.