tb-av, standing off hand, at what you consider a standard rate of fire, your target looks pretty darn good on a 9.5" or so target. I don’t see much from the target that looks like any type of definite pattern.
Reducing your arc of movement or wobble area, is something that definitely requires a steady hand and good practice. Your breathing at this point is critical as oxygenation of the blood has a large effect on tremor, muscle fatigue and your eyes playing tricks on you. Be sure you have a good pattern or rhythm for your breath control.
I may also do a few things when shooting for precision which helps lessen or reduce the wobble area. I may be less concerned with recoil management and I may use techniques that cause less muscular tension in an attempt to reduce tremor. I may go with a “softer grip” on the pistol. I might also use a more “upright” stance, with shoulders slightly less rolled forward. Combine a proper breathing technique and this may help reduce your arc of movement. Lets face it though some people have a steadier hand. If you feel fatigue, stop, put the weapon in a low ready, and breathe.
Another thing I might suggest that you try is shooting with closing your non-dominant eye. I tend do this when shooting for precision, depending. I might also “bracket” my sights. Meaning that I may be using the edges of the sights and perhaps the edges of the rings on your target to come up with a consistent aim point. It can be difficult for older eyes to attempt to see and maintain a small dot as the POA. The thing with this technique is that your groups may indeed shrink, but then you need to be able to correctly adjust and then understand your POI when doing this.
I will add that it is very good if you can start “calling” your shots. It is good that you immediately understand that you may have “flinched” or “jerked” rounds low, but it is also good if you can do similar with your normal shots fired. At least have a good estimation from your sights on target as to where the shot broke in relation to your arc of movement. So you might say that one broke low or left etc…
I know I also say to keep a consistent trigger pull from start to finish, however the more skilled a shooter becomes, we really should be eliminating the pre-travel and “taking out the slack” in the trigger and that becomes our starting point for our trigger pull. Now admittedly that becomes less of an issue or a more fine tuned issue when talking about perhaps a 1911 trigger and how that trigger is tuned. Attempting to make the gun go bang in relation to your arc of movement is almost always a bad thing which can have very negative results as you understand. Besides the tendency to induce a jerk of the trigger, there is still a delay between what the eyes see, the brain processing that information and telling our trigger finger to pull the trigger. Minimizing the movement is the key.
I know that I suggest shooting at distance on a regular basis, as it makes shooting up close seem simple, however I do suggest that a shooter get a good mastery of precision from starting up close. You can more easily maintain a sight picture on a finer point of aim up close. While we should still maintain good follow through, “calling” shots and noticing our arc of movement or how effective we are at reducing it is often easier up close. Once those groups get tight up close start moving back 5, 7, 10, 15, 20, 25 etc…Also shooting smaller groups makes calling shots easier and target analysis easier as you have less clutter, especially if you have changed things that you are doing from one string of fire to another. Marking shots is less practical up close as you start getting ragged holes etc…
Hope this helps!