They are good, but (please take no offense to this) it seems that you traced the model on one axis using a reference image, filled in the faces, and extruded the model to make it look 3D (except for that first model
). When it comes to complex model like guns, try model each part seperately, by modeling in different meshes and then combining into the same mesh, or all in one mesh, and then put it together, this way you can easily make the inner parts of the model (the parts that the player can see anyways). Also, it might be better to round the edges by extruding each sharp edge once or twice diagonally to make a rond edge (during modeling). Cheers
Typos, they can't live without me.