I dont think your expectations are too high.
With suppressed 22 with SUBSONIC ammo it should not be making a crack scaring chooks 50m away.
With mine i cut the barrel down to 13" from 24 and still no crack, there was a small but noticeable increase in noise but still no crack and not enough to disturb nearby animals (unless the projectile was landing near them)
CCI standard that was 1050/1070fps on the box was still subsonic at both barrel lengths.
I never tried CCI subsonic. As i was using Winchester subsonic hollow points
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