Rendering problem with materials and my object

Support Lighting and Rendering
1

I’m designing a custom model and texture for a gun for Fallout New Vegas and I’m running into a few problems.

My first problem is that when I go into texture paint mode, parts of the mesh are missing, but when I go back into edit mode, they’re all where they should be.

This is odd.

anyone have any ideas please?

2

Did you try Recalculating Normals? (In Textured Modes backwards normals will appear invisible -I think due to not receiving any light)
CTRL+N

3

ah. I shall try that.

but I’m not sure if thats the case since when I go into texture paint mode, whole faces of the model dissappear