Ed
I would surmise that a spin of say 10/20 turns per second for a finned projectile would not have much of an effect on an explosion initiating at many thousandths of a second. On the other hand a rifled barrel producing a spin between 2,000 and 3,000 rpm could well have some effect as you say.
It appears that the high tensile penetrating "bolt" is the go now to get the charge igniting after the armour has been penetrated rather than just a surface explosion from squash-head, shaped or conventional HE.
They are getting so sophisticated with Infantry man-carried anti-tank weapons that the tank-on-tank weapons we are talking about are almost superfluous as more than ever before in a conventional war with well equipped armies a tank is little more than a steel coffin and this is not taking into account aircraft like A10's, Mi-28 and Apaches. I think they are brave men surviving psychologically on a hope-over-experience mind-set.
This is pretty depressing if you are a tank man.
https://www.youtube.com/watch?v=CDctxC-7P9k
and this one
https://www.youtube.com/watch?v=y5xKCzdhAC8
And this would make you want to give the game away.
https://www.youtube.com/watch?v=myv7CAJ5Zpk
Lang