A few thoughts on pull force. As with rating the effectiveness of any product, the pull force can be a guide but not an absolute.
Optimum ratings of pull force depend on usage and the nature of the object being pulled. While in a Laboratory setting one can establish a high score for a specific magnets pull force, this score is not always that useful.
If you are depending on a certain pull force and you do not take into account the nature of the object you are pulling then you will not see a similar pull force as listed. The dimunition of pull force is due to many factors such as surface coatings, uneven surfaces, and the composition of the object in regard to its magnetic properties.
Most ratings of pull force are directed from usage on an object that is a flat steel plane. As they say, “Your mileage may vary”.