"Line" problem with texture paint

Hello! I’m fairly new to texture painting, only trying it out last week. I just need a little bit of help with a problem I’ve been having!!..

I am making a primer coating for a Kugelpanzer i just modelled.
2048 pixels dimension
Any help I would be grateful for

Thanks in advance,

It looks to me like you have some serious UV distortion, with lines painted in 2D rather than 3D. Possibly something like a follow-active-quads unwrap, that means that the center of the nipple has a much higher texel density than its circumference.

If you want to paint straight lines, on a 2D image, you have to be very careful about texture distortion. Create a new, better UV map. You can bake it to your original UV map afterwards if that’s what you want.

If you paint in 3D, you don’t have to worry so much about texture distortion-- Blender will compensate for it.