Just built my own take down pins using 2 m6 x 60mm bolts that have a 1-1/2 smooth shank. I drilled a hole in the smooth part and cut the threads off, then used a drill and a file to smooth everything out. A hairpin cotter holds it in place total cost of these for both was 2.49 at Fastenal. cheaper then the HK push pins and its satisfying to make things yourself.
links to the items used
https://www.fastenal.com/products/details/1139575?r=~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600039%20Sockets%22%7C~%20~%7Ccategoryl3:%22600040%20Socket%20Cap%20Screws%22%7C~%20~%7Csattr04:%5E%22M6%20-%201.0%22$%7C~%20~%7Csattr05:%5E60mm$%7C~
https://www.fastenal.com/products/details/0156979?term=hairpin&r=~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600108%20Pins%22%7C~%20~%7Ccategoryl3:%22600114%20Hairpin%20Cotter%20Pins%22%7C~%20~%7Csattr03:%5E15/16%22$%7C~
only took me about a half hour to make them
enjoy your pins
links to the items used
https://www.fastenal.com/products/details/1139575?r=~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600039%20Sockets%22%7C~%20~%7Ccategoryl3:%22600040%20Socket%20Cap%20Screws%22%7C~%20~%7Csattr04:%5E%22M6%20-%201.0%22$%7C~%20~%7Csattr05:%5E60mm$%7C~
https://www.fastenal.com/products/details/0156979?term=hairpin&r=~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600108%20Pins%22%7C~%20~%7Ccategoryl3:%22600114%20Hairpin%20Cotter%20Pins%22%7C~%20~%7Csattr03:%5E15/16%22$%7C~
only took me about a half hour to make them
enjoy your pins
