101Leafy researched the games.
Heavy Bone Gunlance

Based on bone materials, the firing pin is Rajang horn. Very sturdy. Shelling Lv4
| Class | Gunlance |
|---|---|
| Rarity | 9 |
| Attack | 506 |
| Slots | 1 |
| Price | 75,000z |
Upgrades
| Upgraded from | Barbarian Tusk |
|---|---|
| Upgrades into | Hard Bone Cannon |
Can also be made new at the smithy.
Upgrade tree from モンスターハンターポータブル 2nd G 公式ガイドブック (Enterbrain, 2008), page 758.
Materials
Hvy Monster Bone ×5, Blazing Fire Sac ×2, Eltalite Ore ×5, Rajang Horn ×1