There's an old post on this site with a link to Recoil energy..... think 'Neck might have posted it.... I believe the 500 will have over 2x to 4x the recoil of a 270 which is a pussycat........ found it:
http://www.chuckhawks.com/recoil_table.htm
http://www.chuckhawks.com/recoil_table.htm