RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Headless Arrows
The Old School RuneScape Wiki also has an article on Headless Arrows.

Headless Arrows are used for Fletching, a tertiary item required for making arrows. They are made by attaching 10 feathers to 10 arrow shaft, giving the player 10 Fletching experience. They can then be used on arrow heads to create arrows of their corresponding metal.

Spawns in

  • 3 spawns of headless arrows at the Scorpion Pit in level 52-54 wilderness, with a total of 8 available.