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CCT125US, in my opinion pushing down on the gun is the main reason fairly experienced shooters have big misses. So you are in good company. Ball and dummy can help diagnose, but I do not find that it will solve the problem. Here's why: if you are shooting multiple shots with reasonably fast splits, you have to return the gun. As you shoot faster splits, you have to predict when to return the gun. Pushing down on the gun before (or as) it fires is a timing problem. And it's one that I do not believe ever goes entirely away, no matter how skilled the shooter.
A couple years ago I worked really hard to minimize this issue, and I'll describe what I did here.
1. Learn to "turn off" automatic return of the gun. Hwansik Kim has a great drill called Measurement Drill where you fire a shot and let the gun stay aimed up where it recoils. Then you fire another shot to measure how well your grip and stance control flip of the gun. That drill helped me a lot because it's about NOT returning the gun. Now when I shoot steel or very tight shots, I've learned to just let the gun stay up and return it "later". (Note: later is ~ 0.5s.)
2. Minimize the amount of muscle you need to use to return the gun precisely. This is the really deep rabbit hole--maybe the deepest in shooting. Grip, wrists, arms, shoulders, and stance all factor into this. The gun has to recoil, but you can make returning it very subtle. Trying to eliminate muzzle flip is not necessary or desirable. 13 year old girl GMs do this really well, so you don't have to try to be a monster. You can burn a LOT of ammo trying to figure this out.
3. Recognize when a timing issue is happening. I can feel it coming on sometimes when I'm shooting groups--especially weak hand only-- and can often stop the push.
4. Shoot different guns. Since recoil, timing, and weight will be different, you are forced to adjust how you return the gun.
Good luck. I hope this helps. Keep us posted on your progress!
EDIT: @
GJM's post is a good one. He's addressing a possible trigger issue, separate from what I described here.