I applaud that you figured out how to make it work with 223 rifle cases, and are sharing the information. However, IMO, the Dillon 550 will loose market share unless they start selling a 550 casefeeder that can load rifle out of the box. The Hornandy LNL is auto indexing and has a case feeder that works with rifle cases. Besides pistol cases, 223 rifle is probably the most popular round that is loaded in high volume.
Come on Dillon...just do it ! Otherwise we will probably get some BS when we call to tell you that we mangled up all the parts to do this modification, and need some more free parts to mangle until we get it right