I have the Z5 also , you got one heck of a deal,I did do the 25acp conversion and like it alot also.I just got a 340gr 45 cal. mold for bear and moose so I cast up a few and used mmp's orange sabots for the .457 cal. bullet and tried out 5 of them this afternoon to see how they would shoot out of the omega doing a spit patch between shots. During the winter months my target is only 60 yds. out but they all grouped in a 1 1/8" group off a bench with a nikon 3 by 9 scope which is good shooting for me,I'm sure you guys could have done much better,at 65,not so steady anymore , tired eyes etc. I did well for me.What surprised me was the first shot out of a clean barrel was right in the middle of them.I have been considering getting into swaging but maybe it won't be necessary after all.I forgot to add that I used 100 gr. of pyrodex rs.
Have fun with the new Omega