I made my own primer rod out of a piece of 3/8" All-thread.

Run a nut or two on the threads about an inch or so. Hammer the rod into the hex a little at a time. The threads will deform to fit the hole. Use the nut to jack the rod out of the hex.

When you have the rod fully down, lightly file the flats until the rod slides in and out of the hex with no or little resistance.

I am 137 miles from the nearest Home Depot and my local hardware store didn't have hex stock. This kluge worked for me.

R.