Mithril cannonball

Mithril Cannonball is a members-only item on the OSRS Grand Exchange in the bars category.

In-game examine text: "Ammo suited for a boat's cannon."

It has a Grand Exchange buy limit of 11,000 every four hours, a high alchemy value of 36 gp, and item ID 31910.

View on OSRS Wiki

Mithril Cannonball shows an active flip setup with a margin of +9 gp and 647,322 trades over the last 24 hours.

At the buy limit of 11,000 every four hours, max profit per cycle is about 99.0k gp — high margin with healthy liquidity.