Robert,
Im getting conflicting reports here from glock regarding Tenifer remaining after the slide is stripped. The question has been asked here by those interested in getting their pistols refinished.
During a recent Armorers course, and in speaking with Glock and friends in the plating business, I have been under the impression that the tenifer is unaffected by chemicals used to strip the finish on the slide.
I placed a call to Glock today and was told that removing the existing finish with a chemical solution will remove the tenifer treatment, and that the person doing their refinishing uses a light bead blast to remove the existing finish which will preserve the tennifer treatment.
I know you've had a lot refinished, perhaps you could shed some light so we can have a definitive answer.