Years ago, I got rid of many of my sulky threads as they seemed so easily broken. Don't know if they have improved. I also have found that some metallic threads are better than others. I have used RA rayon gold metallic thread successfully, and also Superior thread metallic. While not "metallic" Glide poly thread in gold has a nice sheen to it and is a strong thread. Also slowing down the speed of your machine might help and also making sure the thread is not twisting.