Yes it does. Its been proven repeatedly
Read [url=http://www.reddit.com/r/DestinyTheGame/comments/2sadia/sga_explosive_rounds_and_crit_multipliers_with/]this [/url]
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I've used explosive rounds, then used field scout in pvp. I checked the damage numbers with explosive rounds, then with ought. It added up to the same damage. The same amount of health had been taken away from 2 consecutive head shots from both perks. Tried it in PvE with the same results. Tried doing body shots, still the same. Either my explosive rounds is broken or they do not do extra damage.