so, i’m confused about this uv wrap thingy. i just started 2 months of learning.
I just modelled a shotgun, and there’s aiming barrel made by strecthing cube.
and applied the texture, and it looks so strecthy. Tried to do mark seam but have no idea where i place it so yeah, i just did mark seam, and the texture even more worse stretch.
That unwrap looks kinda weird, might be unapplied transform values.
Try ctrl + A
then select scale and rotation.
Then do the Unwrap again.
About the issues at the edge.
Stretched Textures. It is natural result of the subdivision modifier. You can lessen its effects by adding edge loops closer to the edge. The stretch will still be there but it will be minute.
Seam lines. This is because the colours(from texture) at the UV edges that are supposed to join together (in 3d) are different. Fastest way would be to paint over it with the clone brush. See the topic linked below.