Have a player who's character is a longbow expert, with Clustered Shot feat.
Lets say he shoots two arrows, both hit and the creature has DR 5/- so if he does 10 damage with one arrow and 6 damage with the other, with the Clustered Shot feat we only subtract the DR once, so he does 11 points of damage.
Now, replace DR 5/- with Hardness 5. Do we still add the 10+6 = 16 and subtract hardness 5 once for 11 damage still? Or is Clustered Shot (which specifically says DR) not count and he does 6 damage total (5 off each arrow)?
I ruled, temporarily, that Hardness is kinda sorta like DR so with Clustered Shot the Hardness is only subtracted once, but I told the group that I would post the question and get feedback.
-- david
Agreed with Charon's Little Helper, Clustered Shots doesn't do anything for hardness by the rules. However, I find it to be a little silly for it to work against DR but not against Hardness. Beyond which, Pummeling Style allows for unarmed strikes to do this against both.
As a house rule, it should probably work against both.
Ruling either way is fine, but Hardness is supposed to be "tougher" than DR, since fewer things beat it. And archery is already really powerful in PF, without needing much in the way of buffs.