The utility patents on Primus expired in 2007, it's about time for aftermarket blank manufacturers to make blanks for them.
Does anyone make blanks for Primus blanks ready to accept new side bittings?
Non Primus blanks are designed to not even enter Primus keyways and Schlage only sells Primus blanks with side bittings pre-cut so the technician will only have to cut the standard cuts.