Adamant javelin heads

Adamant javelin heads are items that can be made at level 76 Smithing, granting 5 javelin heads and ??? experience per adamantite bar. They can be fletched into adamant javelins at level 62 Fletching when used with javelin shafts, which are made by using regular logs with a knife, granting ??? experience per 15 javelins made.