I also have astigmatism and shoot both eye's open. If your prescription is correct I don't think it's astigmatism. It's sounds like you have a cross firing issue which I also have. Simply put sometimes your non-dominate eye takes over. In my case the shot picture looks correct but my brain won't let me fire the gun. Phil Kiner describes this as a visual flinch. This may explain why your all over the place on long crossers and closing the non-dominate eye helps. You can continue to shoot closing the non-dominate eye right before the shot or you can use a magic dot.
I have been able to shoot with both eye's open and not have problems with cross dominancy as long as I set up and shoot in a certain manner. These tips may or may not work for you as everyone sees differently and creates lead differently. It has taken me 5 years and lots of coaching to figure these things out. Hopefully I can save you some time and money.
1. Make sure your gun fits. Too much drop and your dominate eye will by occluded by the back of the receiver and the non-dominate eye will take over. Thanks Bob James Montana Long Gun's.
2.When setting up for the shot. Choose your pick up point and set your eye's beyond that point before you call pull. Your eye's can focus from far to near faster than from near to far. This helps me lock onto the target. Thanks Phil Kiner
3. When setting up get the muzzle out of your line of sight. I shoot low gun on all targets but trap. On trap targets I shoot premount but lower the muzzle out of the line of sight. You can't crossfire without a muzzle in the sight picture so I try to keep the muzzle out of the line of sight as long as I can. Thanks Gill and Vicky Ash.
4. Don't move the muzzle until your eye's are locked on the target. Your eye's go to movement so if your muzzle is moving first or faster than the target there is a chance your eye's will go to the muzzle and give that non-dominate eye a chance to take over. Thanks Gill & Vicky Ash
5. Pick a break point and use it. If I don't do this I ride the target and I can have cross dominancy issues. Thanks Mike McAlpine & Gill & Vicky
6. Shoot with a rhythm. This pulls everything together. Lock onto the target, move the muzzle, lead it, shoot it. Thanks Jon Kruger
7. 2-6 above is my pre-shot routine. This was the last thing that came together for me. Everyone has written about this and I have come up with all kinds of pre-shot routines that didn't seem to make a difference. While taking a lesson with Jon Kruger I asked what his routine was and he looked at me like I was from a different planet and replied " don't make this so hard. All were trying to do is break targets in a sport were there is no money to be won" The next station when he called pull I didn't release the target and I asked him to tell me step by step what he was thinking from the time he got into the station until he called pull. He simply watched what the target was doing, figured out the line and his break point and worked his rhythm back words from the breakpoint to establish his hold point. On crossers he used a 3 beat rhythm (move, mount, shoot) trap targets pre-mounted gun 2 beat(move, shoot)
