Bale mass changes because the package contains different metal and void proportions from one batch to another. A common chamber size cannot make aluminium and steel bales weigh the same. If a buyer requires a narrow mass range, combine a defined material stream with a repeatable loading method and appropriate weighing; do not rely on how full the chamber looks.
If the sale or handling limit depends on mass, establish an appropriate weighing method. A visually full chamber is not a weighing system.
State whether bale mass or dimensions are the main receiving requirement. Trials can establish a practical weight range for the actual scrap. Consistent loading and material separation improve repeatability, but a general catalogue weight should not be treated as universal.