If the ballpoint pen spring is too soft u can nest 2 springs together. OR : What i do now is i increase the inside diameter of the factory tbl spring. First i weigh the spring, then i reduce the weight by 20 to 30 % until i get what i want. I use a small round diamond chainsaw sharpening file chucked in a dremel. I do this with clipped firing pin springs too. With a little patience u can get exactly what u want with this method.