Basically the part of the perk Heavy Handed called "Lock and Load" states "While surrounded by multiple enemies defeating an enemy with a Fusion Rifle, Shotgun, Sidearm, or Submachine Gun adds ammo for that weapon to your reserves." The problem is that it doesn't work with 1k Voices, Tractor Cannon, nor Legend of Acrius. I do have an additional arc perk "One-Two Finisher" slotted to activate this part of the perk and I confirmed it works on my Ikelos Shotgun and other weapons I have tested such as Fusion Rifles and Sidearms work just fine.