If you're noticing flinching then nothing else you're doing is going to work until you get that under control.
Trying different things until then will drive you crazy trying to compensate for what really isn't there.
You're gonna have to get the flinch beat before you do anything else.
Practice with randomly empty chambers and light loads. Don't try any magnums until there is absolutely zero flinching with the light loads. Then you can shoot a few magnums with randomly empty chambers, but only a cylinder the first time. If you get any flinching with the mags, go back to the light loads with a random empty chamber until there's no flinch and then you're done for the day. You want to stop on a good note.
Practice consciously relaxing between shots. Bring the gun down to low ready, close your eyes, take a deep breath, hold it, let it out slowly, rotate your shoulders and relax your back. Concentrate on staying relaxed while you take a light breath, raise the gun, open your eyes, get the sight picture, hold the breath and squeeze slowly.
If you feel yourself tighten up during the squeeze, release the trigger tension, drop the gun down to low ready and start all over again. Every time you go ahead and take the shot & flinch, you're training your body to do bad things--the more you train, the longer it takes to untrain. Until things are under control, you don't want to take even a single shot if you feel all tensed up.