This ability is a state trigger. Once it triggers, it won't trigger again while the ability is on the stack. If the triggered ability leaves the stack and the creature is still on the battlefield under the control of a player other than its owner, the ability will immediately trigger again.

Bronze Bombshell deals 7 damage only if it was sacrificed as a result of its ability. If it leaves the battlefield or changes controllers before the ability resolves, it can't be sacrificed and won't deal damage.