This is my version of a bullet tray for the left side of my Dillon 550. The original states XL750 - but the bolt pattern is the same. As the bolt pattern is not perfectly square and symmetrical, I have modified this version to rotate the tray 90 degrees so that it sits a bit further forward. I have found this my convenient.

This is a remix from https://www.thingiverse.com/thing:4357512