At the end of it all the stuff we've posted is all about you holding the gun in a stable manner while you squeeze the trigger.
All the drills mentioned are to help you to learn to hold the gun in a stable and non interruptive manner while moving ONLY your one finger that is on the trigger. All the rest of it is "value added" stuff. Because if you can't learn to hold the gun and move that one finger without moving some or all of the rest of your hands then the rest of the stuff won't help you at all.
Just like a building has to rest on a stable foundation to avoid the walls sagging and doors becoming stuck your gun must rest in a stable non-moving grip in your hands that does not move before, during or after the big BANG!. Unless you can learn to do that the rest of the advice given, hand holding position included, won't help worth diddly.
On the other hand once you manage to learn to hold the gun without any movement other than that ONE FINGER then everything noted in this thread will see you shooting tighter groups more quickly. But without this one foundation ingredient you simply won't be able to see any big gains from the rest of the stuff.
I'd also suggest that you are very much at risk of beginning to overthink the whole thing and lose sight of the basics. And the most basic of the basics is that you need to hold the gun steady in a STABLE grip that does not alter during the trigger pull and through the BANG! event.
For now it doesn't even need to be the RIGHT sort of grip. It just needs to be a stable one.
OK, the soap box moment is over....
So what might be a good drill to start with to test this aspect? I'd say start out with some dry firing at a small spot on the wall to use for the focus point of the sights. While holding your sight picture on the spot pull the trigger smoothly to the rear travel limit. Don't suddenly let go when the trigger breaks. Instead your job is to pull the trigger back smoothly right through the break and HOLD IT at the rear for a good half second before relaxing and racking the SR9 to try again.
Watch the sight picture during all this. Does it jump even a little? If the answer is "yes" keep practicing. Try different amounts of grip pressure. If you're holding it with a tight "death choke" pressure it makes it nearly impossible to move your trigger finger with no effect on your hold. Relax and hold the gun in the same pressure you use for a firm but still friendly handshake. It makes it easier to hold in a stable manner while still allowing for trigger finger motion.
If the sight picture jumps up and down at all at the trigger break then you're flinching or clutching your grip. Work on isolating your trigger finger from the rest of your hand.
It sounds silly but try sticking your index and middle fingers of your support hand up and form a pistol like shape. Grip this with your strong hand and simulate pulling the trigger repeatedly. Concentrate on feeling for changes in the grip pressure along your "pistol grip" fingers. Work on this until you can move your trigger finger without feeling ANY pressure changes along your two "grip" fingers of your other hand.
I know this last bit isn't a typical drill and it is only one handed. But if you can't do this then you can't hold your gun stable either.
Getting back to the dry firing drill. If you see the sights jump side to side at the trigger break with no up and down motion then try moving your finger on the trigger to find the "sweet spot". Assuming a right handed shooter here if the sights kick left at the break then put your trigger finger through onto the trigger a little farther. If the sights break right put your finger through a little less.
When you achieve a stable hold with a neutral trigger finger position then at the click of the trigger break the gun will have a balanced pressure so the release of the trigger break results in just a click with no motion of the gun at all. That is what you're striving for.
My Case For A .22 Handgun-
A LOT of shooters have a terrible time with flinching and other grip stability related issues. The dry fire and other non shooting drills can help with this but in the end you know when there's going to be a big BANG! and when it isn't going to happen. And the mind can play on this so you learn to do the drills just fine but still flinch like a school girl at a slasher flic when shooting live ammo.
A lot of us find that the smaller "bang!" of a rimfire handgun is a happy middle ground. There's a "bang!" and some recoil so it forms a nice transition from zero kick dry firing drills to the bigger kick of a center fire handgun. It worked for me so well that I know have a nice arrangement of seven rimfire handguns that I enjoy both for their ability to maintain my training and conditioned detachment from the recoil of the center fire guns as well as the cheap fun shooting time they provide.
As a bonus your wife will likely enjoy a rimfire handgun as well since you mention that she's not keen on the noise and kick of your SR9.
