Early game
Smelting cannonballs
Use a steel bar at a furnace with the ammo mould for 4 cannonballs. Each steel bar takes 1 iron ore and 2 coal, or 1 coal at the Blast Furnace.
Needs: Dwarf Cannon · 35 Smithing
Mid game
Double ammo mould
Makes 8 cannonballs from 2 bars in one action. It costs 2,000 Foundry reputation, about 75 minutes of play.
Needs: Sleeping Giants · Dwarf Cannon
Granite cannonballs
Add granite dust to steel cannonballs for 5 more max hit on a cannon. Dust comes from the Grotesque Guardians or the Mad Angel.
Needs: 50 Smithing · 75 Slayer or 62 Sailing
Custodian stalkers
These Slayer monsters drop small stacks of cannonballs, plus antlers for atlatl dart tips.
Needs: Shadows of Custodia
Late game
Grimstone forge
The forge in the Grimstone dungeon halves smelting time. With a double ammo mould you make cannonballs 4 times as fast.
Needs: 87 Sailing
Boss drops
Doom of Mokhaiotl drops 200 to 600 at a time, and the Hueycoatl, Corporeal Beast and Nex also drop them.
Port Roberts stall
The cannonball stall never runs out, though you only get 1 per steal.
Needs: 87 Thieving
Hardcore note
Callisto, Venenatis, Vet'ion and zombie pirates drop big stacks, but all are in the Wilderness.
Best monster drops
The monsters that drop the most per kill, from the wiki's drop data. Plenty of these are bosses you'd kill anyway, so the supplies come on top of the gear.
Steel cannonball
| Source | Level | Rate | Amount |
|---|---|---|---|
| Corporeal Beast | 785 | 17/512 | 2000 |
| Phantom Muspah | 741 | 5/235 | 670 |
| The Hueycoatl | 642 | 3/68 | 60–1200 |
| Doom of Mokhaiotl | — | 5/104 | 200–600 |
| CallistoWilderness | 470 | 4/126 | 600 |
| VenenatisWilderness | 464 | 4/126 | 600 |
| Vet'ionWilderness | 454 | 4/126 | 550 |
| Phosani's Nightmare | 1024 | 4/100 | 137–382 |
Drop data from the Old School RuneScape Wiki (CC BY-NC-SA 3.0), fetched 2026-10-01.
Questions
- Is a dwarf cannon worth it on an Ironman?
- For multi-combat Slayer tasks, yes, if you can supply the steel. Many Ironmen save it for tasks where it speeds kills a lot.
- How many cannonballs does a steel bar make?
- 4 with the ammo mould. The double ammo mould uses 2 bars for 8 at the same speed.
- How do I get the double ammo mould?
- Buy it from the Giants' Foundry reward shop for 2,000 Foundry reputation after Dwarf Cannon.
See where you stand
Look yourself up to see which of these you can do now, and exactly what's missing for the rest.