Pistol Shrimp munching on snails?

I have a red candy pistol shrimp...my snails keep disappearing, I just got 25 dwarf ceriths about a month ago and they are all gone...not even empty shells...must have been appetizers..it's either the shrimp or my water but all my params are fine...also my reg ceriths, and nassarius have dissappeared too. I've read they use the shells for structure and sometimes bury the snail alive I'm sure dying snails are fantastic for my nitrates. Anyone else keeping a Pistol with snails? Same story, or is mine special? This tank only has coral, a tailspot blenny, a peppermint, and the pistol for livestock.