What is wrong wrong with this mesh?

I try to model a revolver and it was fine, until i connect front and back of the revolver body body. i try remove double, re-fill the faces and reconnect vertices. it just look weird at some places and i don’t know why




i don’t know what’s wrong since i’m new to 3d
https://drive.google.com/open?id=0B5OMJHHsR0fjMW1abHo4eTJQRlk

Attachments

update.blend (551 KB)

You have faces with inverted normals https://docs.blender.org/manual/en/dev/modeling/meshes/editing/normals.html?highlight=normals

Select all faces and recalculate normals (Ctrl+N)

Before


After


Thank you so much this is help me out a lot