So I recently downloaded a custom gun and dragged all the contents to raw, then the images and weapons to my mods folder. In game, the non-upgraded weapon works completely fine however, when I upgrade it it comes out completely invisible from the pack a punch and when I take it I can only see the silencer and the reticle. https://gyazo.com/d3bf76caed8331d62b6b2bca094cc11a this has been happening to lots of other custom guns and I know for a fact it can't be because of missing contents of the gun. I'm not sure why this is happening but if anyone can help me that would be great.

My guess would be the camo or textures you have set to the upgraded version of the gun is missing from your map. Some custom gun makers set their camo to what their camo is, and in this case since you don't have such a camo in your mod, its invisible. Try alter the model file and checking what the camo is. (Default pap camo is mtl_silver_etching)