This arcane ammunition is capable of storing a spell attack for up to 30 minutes.  The spell can be of up to a level 3 spell slot.   

• To charge a spell into this ammunition, the spell caster may cast the spell (expending the appropriate spell slot) and target the ammunition. If the spell includes a spell attack, the attack roll automatically succeeds. The action cost of this charge is equal to the casting action cost of the spell.
  
  
• On a hit, the target of the spell is the same target of the successful shot and the spell damage (or effect) can be added to the damage of the firearm weapon.
  
  
• One a miss, the ammunition will still explode and expend the stored spell effect, but the target will be wherever the ammunition happens to impact (at the discretion of the DM). 
  
  
• If 30 minutes passes without firing the ammunition, the spell effect dissipates and the ammunition is not consumed (although the spell slot is still expended). 

Notes: Utility, Combat, Consumable