I did a basic edit to help show you some problems i noticed.
The lines are fine, I did not see any issues with pointy curves or anything like that.
BUT
Your shading looks like it does not fit the material it's supposed to be emulating.
You used dithering that looks sandy/rocky/gritty, but the surface is wood.
When your shading a surface make sure that you take a look at some pictures
of what your trying to imitate.
Look at the wood textures here.
As you can see they are made of curvy lines that go in one direction.
So when i started to dither i made the dithering lines that go in one
direction And...... Bam!! it sorta looks like wood.
Also when your gonna make some metal you should take into account
that metal is very shinny and will have some pure white in it even if the color pallet
is far from getting all the way up to white.
you used 20 colors to make the shading on the gun,
I used 11 colors to make the shading on the gun,
The amount of colors does not matter most of the time but using less colors
can help when you have fine details to draw in a small place.
Another thing i noticed about your colors is they have almost no contrast and
very little to no hue shifting.
"hue shifting is when you make your midtone then have the colors move into a warm color when they get lighter and into a cool color when they
get darker"
Because cool colors look farther away than warm colors you can use it to help emulate depth.
Also you can use saturation to help emulate depth, The more saturation a color has the closer it looks and
the less saturation a color has the farther away it looks.
using these in combo helps when your choosing colors.