Anyone notice how the Wands of Spell Striking that you find in Watcher's Keep function a bit strangely? The Pierce Magic ability doesn't dispel Spell Turning, in fact it bounces back and you end up dispelling your own protections. It works on Globe of Invulnerability just fine, though. What's the reason for this behaviour? I've got the patch, no mods.

Iirc wand of spellstriking will remove spell protections and combat protections, my guess is that spell truning doesn't work with the selected type of removal, thus functioning regularly and bounces the pierce magic you send back in your own face.

Have you tried to fire up spell turning on yourself prior to throwing the the pierce at a target, and seeing whether it'll actually dispell your own spell truning?
The function of spell truning is after all to bounce spells back at the caster, and it bounces at all levels.

From the BG2 manual:
(Pierce Magic)
It will cancel one spell protection of 6th level or lower on the creature. The list of spells that this includes is Minor Spell Deflection, Minor Spell Turning, Spell Deflection, Minor Globe of Invulnerability, Spell Immunity and Globe of Invulnerability.Pierce Magic shouldn't work on Spell Turning as ST is a level 7 spell.

hmm.. In the item file for spell turning, it actually has bounce spell up to lvl 9 spells iirc..

When using Pierce Magic as a spell or from a scroll, it does dispel Spell Turning. It's only when you use the wand, that it doesn't work.

EDIT: I experimented a little, taking two characters with Spell Turning and having one use the wand on the other. It bounced back and forth until the spell levels were consumed.