When your metallic 3D model’s texture stretches in Substance, it’s almost always due to poor UV unwrapping that doesn’t align with the model’s geometry.
UVs act as a 2D "skin" for your 3D model—if they’re unevenly scaled, overlapping, or don’t follow the model’s natural shapes (like curves or edges), metallic finishes (or any texture) will appear stretched. This often happens when UVs are rushed, use too few seams, or aren’t adjusted for complex surfaces.
To fix it, open your model’s UV layout in Substance (use the UV view) and look for distorted grid lines (a test pattern). Try re-unwrapping the model with more strategic seams or using Substance’s UV tools to evenly scale problematic areas.