Explosive Rounds

Explosive Rounds is a weapon perk that explodes on impact, dealing a portion of the weapon's damage in an area.

Effect: Upon impact, your bullets cause explosions with radius of 2 meters. Targets closer to the epicenter take more damage.

Explosive Rounds offer 50% additional damage on chest hits to normal mobs, 13.4% additional precision damage to Cabal and 33.4% additional precision damage to Vex. My data also shows that the Cabal crit multiplier is 2.14 while others are 3.0.

There are other factors that come into play and will affect triggering things on headshots (Firefly, Gunslinger's Trace, Chain of Woe, etc.).

While Explosive Rounds give a massive damage increase on regular mobs (up to 50%). It does not increase your damage in PvP and killing Majors or Ultras.

• Elemental Shields - Whereas weapons that don't have a burn matching an enemy's elemental shield do little damage, weapons with Explosive Rounds do damage twice, once with the bullet impact and once with the explosion. The explosion damage deals bonus damage to elemental shields and helps kill shielded enemies quickly. This works very well with the Matchgame modifier active if you don't have a primary with the required elemental burn.
• Range and Damage Drop-off - Although the impact from the bullet suffers from damage drop-off at range like regular rounds, the explosion damage does not. So even from great distances you are still able to put significant damage on enemies.
• Explosive Rounds and Firefly - A common misconception is that Explosive Rounds break Firefly. This isn't entirely true. As stated earlier, Explosive Rounds do damage twice. If you shoot an enemy in the head and the impact damage is enough to kill the enemy, it will proc Firefly. However, if that impact damage doesn't kill the enemy but then the second set of damage, the explosion, does kill the enemy, that's when Firefly won't proc.
• Specialist Modifier - When the specialist modifier is active, special weapons do 2x damage, but primary and heavy weapons are dropped down to 0.7x damage. Although this affects the impact damage, the explosion damage from Explosive Rounds still deals its regular amount of damage.
• Phalanx Shields - Those pesky Cabal holding shields may be a pain for some. Not only shooting at the ground, but even shooting directly at their shields deals damage to them from the explosion. A good way to stagger them if you can't hit their foot or arm.
• Multiple Enemies - The Explosive Rounds are able to hit multiple targets if they are stood very closely, almost like a much weaker version of firefly.
• PvP - Being shot with an explosive round results in a flash on the recipients screen. Some people may find this off putting which could help you kill them if they get slightly disorientated.

• It splits the damage output of your weapon - dealing half as the physical connection and the other half as the explosion.
• It does not boost the damage output of the weapon in any way.
• Overall damage dealt is reduced when dealing precision damage.

Example:

• Without Explosive Rounds: Base damage (Standard) dealt to Vandal - 87, Precision damage - 261
• With Explosive Rounds: Base damage (Split) dealt to Vandal - 44 physical/44 Explosive; 88 total, Precision damage - 174 physical/44 Explosive; 218 total

With explosive rounds, the physical component of the damage gains a weird modifier (somewhere around 4x), but because it's only half of the standard base damage, the math actually works out to applying only a 2.5x multiplier to the standard base damage as opposed to 3x multiplier it gets without explosive rounds.

Obviously, this neglects the total amount of damage done by its splash effect to multiple enemies in the (very) near area of the target, but in terms of taking out a single, high-priority target, Explosive Rounds will decrease your overall damage dealt.