Lucky Break provides the player with additional ammo and crafting items from supply boxes. However, this does not affect supplies needed for clan integrity themselves, nor does it affect the ammo collected off of enemies. Each rank of Lucky Break affects what type of additional supplies are dropped. Rank 1 grants 50% more pistol ammo, rank 2 provides 25% large firearm ammo and 2 crafting ingredients, and rank 3 includes all of rank 1 and 2's perks, plus 3 crafting ingredients when a supply box is opened.
On occasion, loot boxes can drop very low quantities of supplies, making the effort used to reach them all but wasted. This skill guarantees that reaching loot boxes is almost always a worthy endeavor.
Loot boxes tend to have worse drops when the player and his/her team is doing well in terms of kills and interrogations, while having better drops when the opposite is true. Thus, Lucky Break is not necessarily a very useful skill to equip when one's team is losing.
Lucky Break is a good skill to equip when one is attempting the Gifting challenge. Whereas one might normally experience the bad luck of being on a winning team and therefore not having enough materials to craft with before time runs out, Lucky Break ensures that this scenario rarely becomes a possibility.