Aw Nuts

Lesson learned: not all steel is created equal - check the grade!!  I had high hopes that I'd be able to cut the 5mm JIS screws, but ended up killing the die instead.

I found a couple of socket cap screws (#4 hex) at ACE that had a good length of un-threaded metal.

For my first attempt, I cut the screw thinking that I could just get the unthreaded part to bite into the die.  But it wouldn't catch (and I only realized why later).

So then I tried cutting most of the length, but leaving enough thread so I could get it started in the die.

Then start cutting.  This was all going very well until the screw seemed to turn without moving.  I figured it had just hit the unthreaded metal and needed more downward pressure.  I was wrong.

Had to knock the screw back out with the ball peen.  Upon inspection, it looks like the threads pulled the metal down but instead of being cut, it simply flattened the grooves in the die.

Could it be because it was 12.9 grade steel?