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Hey Amahu, were you using both the OpenLOCK sets for Rampage castle and Stalingrad sets, or was the Stalingrad set the non-OpenLOCK version? The OpenLOCK models have an extra section added to their bottoms to accommodate the OpenLOCK clips, so this might make the heights different.
One thing I quite like to do when I’m re-scaling is use a program like Mesh Mixer to check the relative scaling of the models against each other. I will get one to a size I like and then bring in the others, scale them down and then tinker until they are perfect.