Item models are now limited when using the display tags "scale". In previous versions, you could use massive scales and it was a really useful feature. However in 1.8.1 pre-5 it gets limited when the scale exceeds a value of ~2ish (Not tested for exact value). Screenshots show the difference between 1.8.1pre-4 and 1.8.1pre-5, using an item model on an armor stand using a 16 scale. I also included the item model I am using.