G17 shooting left

[ar15_dude]

I have two G17s (one a Gen2, the other a Gen3) that both shoot left, requiring the rear sight to be at or just past the right edge of the slide. Before you say I must be cock-eyed, my other Glocks shoot straight with the rear sight centered. I checked the slides for cracks at the ejection port, found nothing,

Why is this, and can I correct it?

[JR]

Sounds like a fit issue to me. Look at the point where the barrel exits the slide. Is the barrel held to one side?