Mesh seems fine in substance painter, looks weird when exported

[Raven23855409lggv]

Hello

I've been making weapons for a game called Garry's Mod for a while now and have encountered this issue sometimes where my weapon's mesh looks fine in substance painter but not when exported and in-game. I'll attach some pictures down below so you can get a good view of it.

Is there anyone that can help me alleviate this issue?

Many thanks.

[Ethan Olson]

Hey Raven, 

What bit and padding are you exporting with?