I would have used a bench vice to hold the 4" grinder and then a couple of V-blocks to spin the strut tube on. Would take less than a minute to cut each spring perch off and would make it a perfectly straight cut for all four...

http://www.bnmotorsports.com "And I will strike down upon thee with great vengeance and furious anger those who attempt to poison and destroy my CEG brothers. And you will know I am the Moderator when I lay my vengeance upon you."