I think about six were made ,the last one sold on Saunders website about 7 or 8 years ago ,a fellow in the U.S i was going to buy M98 Bottom metal for a 500 Jeffery, told me he made them up for an Australian concern, but they did not take them all ,and still had a few left, i cant remember his name, Duane Wiebe makes the bottom metal for a 500 J also.
Rolf Bachnick told me some years ago he would not make another staggered magazine again for a 500 J, only a inline with clips, which he said worked perfectly and sold one to i think Graham Williams in the NT .