No, they don't.
Firefly is what you mean and that causes the explosion ;)
Explosive rounds is a useless perk
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Firefly perk causes explosion with precision kill. Explosive rounds make explosions on impact regardless of where you shoot. Firefly is better.
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No, I know what perks in talking about. I'm talking about explosive rounds.
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Explosive rounds suck. Firefly is the one to have.