Wait...you aren't actually using probes?

I wouldn't use something different, especially if you aren't completely a pro at it.

I go by how many scales deep it went, not by centimeter, as a larger snake has larger scales, so its not as accurate without being there.
Three and below is female. Four, and I ask hubby to check it. Five to 7 is male. I have never personally seen a snake go past 7.


As always, your mileage may vary, but this seems to be a good rule of thumb.