Shooting left with a Glock?
I had the same problem with my G23 and I see it a lot here in the posts. I realize there are other things that can cause shooting to the left but it seems to me many people have that problem.
I went to the range Thursday and asked the armorer there - Why is it I shoot just fine - as good at least as I shoot - with my Sigs and the Glock always groups to the left? Of course the first thing he asked was about trigger control and I replied it is good. He got the rear sight moving tool out - moved the sights over to the right and now I'm grouping center mass.
My point - it's not always the shooter and don't hesitate to move those Glock sights.