A mag will change if you feed it within level 50, not just at the level up.
In order to avoid the mag changing between character/class switches, try to get it out of the divisible by 5 levels.
Honestly though, past level 50, feeding mags is less strict as you've gotten the PB that you wanted by this point. Just check the feeding chart for it and adjust.
In order to avoid the mag changing between character/class switches, try to get it out of the divisible by 5 levels.
Honestly though, past level 50, feeding mags is less strict as you've gotten the PB that you wanted by this point. Just check the feeding chart for it and adjust.