@angel eyes what is the diameter of the circle, 4"?
Like you, I was in my sixties when I did DSC1 and was due for cataract operations a few weeks after it. I had to use the rifles available from the trainers and couldn't get a clear sight picture with either of them when practising. On the day of the test one of the trainers brought a different rifle, a really nice CZ in .243, and I got on with the scope. With that rifle I was able to put all my assessed shots into a 2" group. If that rifle had not been available I would have struggled and had resigned myself to redoing the shooting assessment at a later date after my operations.