[NefariousKoel]

I've had much success using only Contact on them.

Perhaps part of the problem is that the contact/contact& influence setting will reset itself to it's default Contact&Influence setting if you don't fire fast enough.

I have had quite a few default to that just before I hit the fire button. The influence detonators on the stinkin things almost always blow up on their own before getting very close to the target. Way too touchy those magnetic detonators.