The round hole front apertures would probably help a lot. My biggest issue is the distortion of the target as it gets closer to the top of the front sight. I haven’t heard anyone else talk about that so it might just be me and my eyes.
What you are seeing with the distortion of the target as it starts to approach the top of the post is light reflecting off the top surface of the post. Old .303 saying is 'light up, sight up' as you naturally hold the sight down to stop the distortion - not needed the same with front rings.
The issue with the wondering zero you are having is likely to be a mixture of various faults
- inconsistent body position for approaching the rifle so head position is changing with respect to sight, recoiling differenly.
- forcing the rifle into aim, rather than moving body between targets - try the 10+1 smallbore targets with one shot per aiming mark to see this. You naturally will move to natural point of aim when you fire.
- how the sights are mounted on the rifle - target/match rifles have very repeatable and stable ways of doing this and we all develop ways of ensuring this happens.
- quality of the ammunition used - solid round nose (Lapua/SK/RWS- or the bulk T22/TAC etc, the Elly EPS style is included), no hollow point or plated used. It can be even down to the batch of prefered brand - pray it likes the cheaper end not Red Box Tennex or Midas level.
- sorry to have to say this but 'you' can also be the problem - you think you will have problem X and cause said problem. Get someone else to do some testing of the rifle and ammunition combination to see if it holds true.
Fixes:
- Have a set way you set up the rifle and position before you start - get down the same way each time.
- Change said position when changing which face you are engaging - the rifle has moved alignment so you do too to keep the relationship the same.
- Test the ammunition batches to see which one the rifle likes and bulk buy the best one, better to do indoors and out of a shooting vice if possible. The top guys go to the manufacturer testing center to find this and then get the entire batch.
- If using a standard factory rifle, the barrel may just be well 'average' and shoot anything OK but nothing fantasticly - find a good gunsmith and have them fit a replacement match grade barrel (10/22 have plenty available either factory or custom). Have them also check the action out - you may unfortunately have one that is 'in tolerance' but all over the place with the relationships between vital ones.
- As for you, well fitness helps, not being tired/hungry/rushed helps, being in the right frame of mind - going to have a good shoot, firing good shots, etc helps. Be honest with yourself - that was a good shot fired or whoops it went there/bad release/didn't feel right etc - we learn more from these than telling ourselves porkies.
We all go through this and at some point we find what works for us, then wonder why it didn't happen sooner and we didn't figure it out seeing as it is now so obvious.
So go out, make money into noise and have a blast.