That is also impossible, you can't change turret rails into regular rails.In that case it might take a few extra steps but if I am not mistaken you could set up logic to switch the turret axis to a regular rail pull the items and then have another set of logic to turn them back into a turret axis
There are only 2 new ways I have found to get cargo off of turrets (ignoring the old method of physically walking to it).
One is using the personal storage option, the second is having a cargo crate docked to the turret, that can be moved, undocked, and swapped to the main ship on its own.