WarframeAlchemyLab ES
Ammo Drum

Farming plan

Ammo Drum

Arsenal: Ammo Drum
Dropped by
Hellion Power Carrier Uncommon 6.32 %
Another Betrayer, Rotation A Rare 2.21 %
Family Reunion, Rotation A Rare 2.21 %
Hot Mess, Rotation A Rare 2.21 %
Recover The Orokin Archive, Rotation A Rare 2.21 %
Sunkiller, Rotation A Rare 2.21 %
Table For Two, Rotation A Rare 2.21 %
The Aftermath, Rotation A Rare 2.21 %
Time's Up, Rotation A Rare 2.21 %
Orb Vallis - Enrichment Labs Enemies Common 1.73 %
Eidolon Vomvalyst Uncommon 1.26 %
Axio Crewman Uncommon 0.76 %
Chance of getting it by number of runs
0% 25% 50% 75% 100% 10 20 29 39 49 11 runs · 50% 11 runs · 50% 36 runs · 90% 36 runs · 90%

Each run has a 6.32% chance. The curve is 1−(1−p)ⁿ: there is never a guarantee, only growing confidence.