101Leafy researched the games.
Black Cannon G

Crafted with the latest methods, it looks the same, but causes G-Level damage.
Every shot from its wide bore lets out a thunderous boom. The sound is called "the Black Dragon's roar," and without a strong will, even its owner may lose the will to fight the moment it fires. Because it reloads quickly, only a hero who can bear the constant noise can draw out what the weapon is truly made for.
Our translation of 復刻 ハンター大全 (KADOKAWA / Enterbrain, 2014), page 172.
| Class | Heavy Bowgun |
|---|---|
| Rarity | 10 |
| Attack | 408 |
| Slots | 1 |
| Reload | Fairly fast |
| Recoil | Medium |
| Table price | 10,000z |
Listed in the equipment tables of 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 795.
Ammo
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 795.
Materials
Commendation S ×1, Dark Stone ×10, BigEDragonJewel ×1, Giant Blk Pearl ×5