While many others, here, shooting the CZ-40B prefer the 165 gr. bullet/round, mine seemed to prefer the 180 gr. Which made me happy, as it was far easier to come by from my usual sources.
6" at 25 yards can probably be improved on -- and probably will be as you get more familiar with the gun.
(For me, it often takes 2-3 range sessions before I start shooting a new gun as good as I can shoot it. Something about a new gun just throws me off. A friend of mine, however, can drive tacks with new guns -- and I often get him to shoot mine before I do, to give me an idea of its potential...)
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With regard to old eyes -- I have them too -- check with your eye doctor the next time you get your glasses renewed. I had mine prescribe an extra pair with the right lens (I'm right handed and right-eye dominant) set to focus on the front sight, and the left lens set to focus on distant objects.
It takes some getting used to, but it has helped me.
Its a LOT more important that you see the front sight (and its alignment with the rear sights) clearly than you see the target clearly. A LOT.
The other night in an IDPA classifier, I managed to shoot the final stage -- most of which is at 20 yards -- with only 5 shots not in the 8" center. (That's 25 of 30 rounds relatively where I wanted them to be...)
I still missed expert by 6 bleep seconds, though!! I think I've reached my level of maximum incompetence.
My consolation is that the only guy who had a lower score on that stage had a lower score because of his speed, not because of acurracy. (He's almost 25 years younger than me, and shoots a lot more with a gun that cost 4-times what mine cost. And he practices a lot!! [excuses, excuses, excuses] He is very good -- he missed master by 8 seconds.)