Massive Entertainment designed the revolver drum slot to be static for balance reasons. Revolvers are high-damage, high-accuracy sidearms with slow reloads (either one-by-one or via a speedloader). If you could slap an extended drum mod on a revolver, you’d effectively create a pocket rifle with 15+ rounds, breaking the weapon class’s intended weakness.
Since you cannot add a physical magazine mod to a revolver, improving its performance comes down to: Division 2 Revolver Drum Slot
This is where many players get lost.
Players must increase a Control Point's alert level by completing linked activities (broadcasts, public executions) before attacking to ensure a blueprint reward. Massive Entertainment designed the revolver drum slot to