Why am I breaking penetration rods?

Since 1982 it has been debated on stiffness, elasticity, realization, hardness etc. etc. of the Penetrometers auctions.
There is no doubt that those who make tests sooner or later some auction or tip must break it.
I kindly ask colleagues not to complain to us about breakages.

Over the years we have achieved:

the rigid steel rods C40-39NiCrMo3 but “broke” and not good,
we made them elastic and “vibrate” and it’s not good,
we made them malleable and “bend” and it’s not good,
we made them Male-Female and “break the fillet” and it’s not good,
we have made them Female-Female and “unscrew the grains” and it’s not good.

If you do not want to run the risk of occasionally breaking an auction …… or tap slowly or do Cartography.