Shading troubles

Hi there, I’m new to this forum and kind of a newbie in blender.

I am currently modeling some assault rifle for a short animation and i’m running across some trouble in my renders.

As soon as I hit the “smooth” button, the shadows are all messed up, and I can’t find out why. See for yourself :

Solid - No problems…

Smooth - Bah !

Here’s the wireframe.

The same thing is happening on other parts of the gun.

If I remember correctly, this happened a few other times with other projects. I never found any explanation or solution to the problem. This is kind of fustrating.

Sorry for any spelling or grammatical error, English isn’t my main language.

Try to recalculate all Normals outside.
(Select all Faces and hit Ctrl/N)

add some edge loops.

press the K-key while in edit mode

while ur model is smoothed, press the ‘autosmooth’ button, it should be in the same tab as ‘set smooth’ and ‘set solid’.

autosmooth worked, thanks guys