I am getting this weird edge around this barrel i am modelling which is nopt covered by the wood texture. My thought are on the uv unwrapping but what does it help to be correct if i cant fix it? I) have provided a picture, if this isnt enough i am happy to up load the model at paste all or something else.
Some observations ;): tons of double verts. Ngons are bad for texturing (mostly, triangulate is better, Grid Fill helps). UV unwrap - Follow Active Quad (one quad should be selected, unwrapped and straightened out in UV space, then select all and this straightened face as active, last). Scaling in UV space - 2d cursor as a pivot helps. Mesh Auto Smooth on Object Data tab helps.
http://www.pasteall.org/blend/41163
Btw, textures were not in the file (File, External Data, Automatically Pack) but i think this border was uv scale issue.
If i understood correct you are saying i should triangulate my model? Anyway, i inserted an edge just below and deleted the part. It took care of the problem. I also found the double verts and deleted them manually, “remove doubles” didnt have any effect.
In general, before paint or bake, yes, triangulate is better than leave n-gons. Also, for a low poly there is a reason to triangulate all mesh: auto triangulation of quads will happen during render and automation could change desired shape.
Remove doubles could have needed threshold adjustment but delete loose faces in your case and W - Bridge on two selected vertex loops can do too.