usually, low and left for a right hand shooter means you are slightly jerking the trigger in anticipation of the recoil. Agree with the above posters....concentrate on a smooth squeeze of the trigger.
Would also suggest practicing by dry firing the Glock and practicing a smooth trigger stroke. With no round in the chamber, squeeze the trigger concentrating on where your front sight ends up
after you have "fired". Your sight should not move.
Dry-fire 20 time per day for a week. Then go to the range for some live-fire. Concentrate on you trigger control just as you did in dry-cire. You will be amazed at you results.
One handed shooting and shooting the longer, heavier trigger of your other gun is the same issue. You are concentrating on your trigger pull and therefore you are not yanking it off line.
Keep practicing the fundamentals of sight alignment and trigger control.
Yup, both eyes open! Also, lots of dry fire practice will generally help this. The good news is this happens to the vast majority of us and it will go away with practice.
I shoot with my non-shooting eye closed, and don't shoot low left. If I slap the trigger, I shoot low left.
I had same issues when I first started shooting my new Glock 34 Gen4. I was mainly a 1911 shooter, so the long, creepy Glock trigger pull took a LOT of getting used to, as did the grip angle (different than a 1911). I did a "25 cent polish" on the trigger parts and that helped some. But what mostly helped me was dry firing the gun at home. I think the longer trigger pull has a tendency to bring in additional hand muscles. That is, it's hard to move just the trigger finger a long way, without the other fingers starting to come into play a little bit. This then naturally draws the gun low/left.
I practiced dry firing until I could limit all the movement to my trigger finger alone - I had to consciously disconnect my trigger finger from the other 3 fingers. Then my groups really started getting tight, and on the money.
Hope this helps.
EDIT: one more thing that I have really been working on is eliminating the 'flinch'. Even a tiny flinch can cause you to miss. When I go to the range, I try to emulate my dry fire practice, especially with regards to flinching. It's easy to have zero flinch when dry firing, but MUCH more difficult when you have that live-fire BANG at your fingertips! It's fascinating to watch the shooting shows and see that most of the guys flinch somewhat. I have only seen a few who demonstrate virtually no flinch.
Dry fire will tell you if you are pushing the gun. I would suggest first... finding someone that can explain a high thumbs forward grip and a neutral stance, and why... as well as determining how much finger you should have on the trigger. Start with your pad center. Dry firing, once you have established some basics is a great way to learn the trigger and to separate, in our little brains, the act of pulling the trigger from the explosion, death and destruction of all mankind, that is caused by it. Two eyes open is not a deal breaker but is preferred. Definitely shoot with your dominant eye. The more you DF, the more natural everything gets. Good luck
7 o'clock usually is jerking the trigger for a righty. If I was coaching you on one of my ranges that's what I would suggest. Slow down the trigger pull.
In many cases it takes much, much trigger time with many rounds downrange to keep from jerking the trigger. Keep both eyes open and use earplugs AND earmuffs. Recoil isn't gonna kill you.
I had the same problem (low and left) no matter what pistol I was shooting. Here is what solved it for me:
1. Not enough finger on the trigger,so now my trigger finger is on almost to the joint;
2. I was moving or clenching my three other fingers when pressing the trigger. Practiced moving the trigger finger (empty handed)while keeping the other three fingers perfectly still; and
3. Tighter grip on the support hand and less tight on the firing hand.
I think the overall effect was to improve the straight back trigger pull, while keeping everything else as stationary as possible.
OP, you say that the problem is less if you shoot one-handed. That suggests to me that it is your left hand causing the difficulty. How do you position your left hand? Do you have your left index finger on the front of the trigger guard by any chance?
A recent gun rag article suggested balancing a penny on the front sight while dry firing until you can keep the penny from falling off. Like I can get the penny to stay on without pulling the trigger.
OP, I too am a right-handed, strongly left-eye-dominant shooter. Have you tried shooting two handed and canting the gun about 15 degrees counter-clockwise to bring the sights in line with your dominant left eye?