[Damage Reduction][1] reads: > Whenever damage reduction completely negates the damage from an > attack, it also negates most special effects that accompany the > attack, such as injury poison, a monk's stunning, and injury-based > disease. Damage Reduction does not negate touch attacks, energy damage > dealt along with an attack, or energy drains. Nor does it affect > poisons or diseases delivered by inhalation, ingestion, or contact. > > Attacks that deal no damage because of the target's damage reduction > do not disrupt spells. For purposes of [Hammer the Gap][2], it just requires you hit, so I'd say it's fine. Obviously there's some GM interpretation here of what "most special effects" means, so there is no RAW-perfect answer except your GM's ruling. [1]: http://www.d20pfsrd.com/gamemastering/special-abilities [2]: http://www.d20pfsrd.com/feats/combat-feats/hammer-the-gap-combat