I posted earlier in the thread Bout the Triple K mags. They have been doing them 6-8 years that I know of. Im happy with them. I parked all of my factorys and went wjth those.FWIW Mod 52 mags can be modded to hold 6 rounds and even heard of 7 rounds working.
I did mine to 6 rounds when I was shooting combat leagues in the winter with 6 round strings.
Original mags are probably to valuable to do the mods too now but aftermarket(triple K I believe is doing them) would be ok to mod that way.
Good luck getting the gun OP.