Greetings @-BW-,
I am not surprised that you are getting better results with 30-06 brass. Resizing will only be reforming a little of the shoulder into neck so you are mostly neck sizing and setting the shoulder back a couple of mm. I suspect that you length to the neck in your 7x60 is around 51 to 51.5mm with the .30-06 53.62mm. The 7x64 is over 55 mm. There is a wildcat 6.5mm case rolling around on my bench that was made from a 30-06 case that has a length to shoulder of around 50mm and has formed nicely.
Regards Grandpamac.
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