Hey @Ironbelly! Thanks for that! With the files you’ve sent me, I was able to investigate why this happens. The “T3D” files happens because the PNGs were saved in grayscale, not RGB. The Normal textures loses during export because PNG was saved in 16-bit instead of 8-bit (UE4 cannot properly export it).
If you could please check an email that I’ve sent to your support address some days ago, I’ve also sent you the fixed textures. Unfortunately, now that I’ve been through this process with a bunch of your other weapons, I could write you a list with 3 or 4 others with similar issues (and many others that went A-OK hehe).