The alpha AK states it fires 7.62x39mm but in the 3d model, it shows the 5.45x39 magazine and caliber.
Here is the alpha ak, notice the caliber appears to be 5.45x39. }
Here is the akm, chambered in 7.62x39. Notice the larger caliber when compared to the alpha ak. This is what the caliber should look like if the alpha ak fires 7.62x39.