If you have a Barracuda chuck I just found a store that carries the screws the ones I bought they said are between a grade 5 & grade 8 in hardness.I had to buy a box of 100. The screws fit perfectly I brought my chuck with me to make sure I got the exactly the right size. They were only $11 for a box. I did try them & they do seem a lot harder cause I tightened it very hard & didn't feel like I was rounding out the allen hole of the screw.
I may have some left over so if I do & anybody wants me to send you some please PM me your address & I'll send them.
Here are the type & size of them.
I also purchased some of the 1" ones to make my own "cole Jaws"