Please consider making custom kill rank be the real numbers required instead of an linear between the first and last.
example of current state of afairs:
if one where to place rank 1 at 300 rank 2 at 750 and rank 9 above 120000, for rank 2 you would need effectively 15k and whatever you put for rank 3 would need 30k. making this quite a useless feature, to be fair the description of said setting does explain this.
I get this is nice for linear progression of turret abilities, but I personaly like the idea of a exponent like progression where the first few ranks barely increaase the abilities of said turret, where as older more veteran turrets that have served the border guard more be much more valuable.
ofcourse this is all personal preference, but there is virtualy no point in coming up with custom kill ranks, unless its linear.
Anyway, thank you for your time reading this.