Herm Sprenger Prong Collar Question/Issue

Heyy yall, I have a 65lb pitbull/boxer mix and I got both the Herm Sprenger Prong Dog Training Collar Ultra-Plus Chrome Plated Steel in the 2.25mm and the 3.0mm.

I have been having issues with these two collars fitting my pit mix correctly.

The 2.25mm is too small while on the 3.0mm he is between sizes and only needs a half link removed not a whole link or it becomes too small.

I am also scared since he is a strong puller that if I order extra links for the 2.25mm and hopefully it fixes that it might break or come undone due to how strong he is.

Please give me some advice🙏🙏