When firing a strength arrow from a stack of 2+, it reduces to 1 in the inventory, however when picking back up the arrow that was fired, from the ground, the stack increases to about double (just one less because it counts after the arrow was fired).

1. Gather 2+ strength arrows
2. fire an arrow at the ground
3. pick it up
4. you now have (Amount of original arrows) + (amount of arrows after fired) — For example if you shot with a stack of 4, you would have 7

MAX of 63 being added to the inventory.