I also made my own gauge and modified cases. But instead of using the 5/16 x 36 i used standard fine thread 5/16 x 24.
The tubing is 1/4" ID stainless, the rod is 3/16 brass brazing rod, end piece is stainless bored and knurled, only thing purchased was lock down screw.
Cases are made on lathe, drilled with 9/32 and tapped, flip the case around and relieve the neck with emery cloth and 1000 grit paper wetted with WD-40 until very light tension on the bullet.
Works great, but have to make your own modifed cases because of 24 pitch thread. I need to find a 36 die.