This is KINDA a PSA (and half blogpost). I just felt I had to share it. So here goes since I know someone might be experiencing this same longing issue.
My Glock actually shoots left. No, not low left. Just left, ever so slightly, we're talking about a 2 to 3 millimeters at 7 yards, and you can start noticing it pretty heavily the further out you take it. Funnily enough, I became a pretty competent shooter on that particular Glock 34 in USPSA. That slight group to the left never really affected my ability to score since it's so miniscule, but it always bugged me. Everywhere I looked online, people said it was the glocks grip angle, or perhaps it's squishy trigger with false walls, they said the most likely culprit was "milking the gun", or "not using my support hand". I always found it interesting that an M level shooter couldn't shoot his gun straight. Then I bought an M9A1, which I shot perfectly centered. My father gave me his HK USP, which I shot perfectly centered too. I ditched the G34 and I started competing with an Elite LTT because shooting ever so slightly to the left with the G34 always bugged me on a personal level (or when playing around with steel poppers at 100 yards). For years I believed I was the issue because if you mention the word "left" on any pistol forum, the first thing you get told it to "GET TRAINING BRO". Then I went back to the Glock thinking that perhaps, by now, I would have grown out of my "puling it to the left" issue, after years of competing and winning some good matches. And when I shot it again, it STILL shot slightly to the left.
So I decided to get to the bottom of it. Was it really me? First thing I did was get a buddy of mine who competed in Bullseye, granted he didn't like Glocks, but he did shoot a little to the left with it. Just like I did. Of course, I benched it, I had him bench it, it always shot a little to the left. But I wasn't happy with those bro science results. So I put it in a vice. We had to invest quite a bit of money into a quality vice that has never been used after that experiment. And yes, the vice DID confirm, that the Glock was in fact, shooting left. The ammo didn't matter, no matter what you used, 115, 124, 147, etc, it always shot a little to the left. Now, I know that guns aren't PERFECTLY zeroe'd from the factory. And that you have to finalize the zero yourself, but we actually had to drift the rear sight WAY to the right to get the shots to hit centered in that vice, it looks weird having the rear sight close to going outside of it's dovetail. With no other pistol that I've ever shot, have I actually needed to drift the sights. Whenever I installed night sights or fibers on any other gun, I always just aligned them perfectly to be centered with the slide and they always shot POA/POI. So it came as a surprise to me, that not only did my Glock need drifting, but it needed A LOT of drifting to have it hit POA/POI at 25 yards.
So I decided to get the Glock milled for a red dot sight, and I had the rear sight moved forward of the optic. Once the Glock with its red dot was zeroed through the bench and checked for true mechanical zero on the vice... We moved the rear irons to match with the dot. The rears had to be drifted the same amount and to the same direction as before, so that the dot would be evenly in the middle of the front sight when the BUIS were in alignment. I then decided to take out the G34 with its new red dot for a spin. I took it to a class with Scott Jedlinski, I had him personally shoot it, and he said it was perfectly zeroed despite the rears having been drifted all the way to the right. I'm not a gunsmith, but from the gunsmiths I have talked to about this, they told me I should try to get the barrel fitted, or buy an aftermarket barrel, while a Glock armorer told me it was the locking block and I should consider changing it. Quite frankly, I'm tired of spending money and time on this endeavor, maybe this is how most handguns are and I just got lucky with my Berettas and HK's mechanical zero in relation to the sights/slide alignment, and I have made a mountain out of a molehill.
Sometimes, it really is the handgun.