Ian
Notorious member
Brad have you seen the lee universal expander die?
It has 2 interchangeable expander plugs. The angles of it aren't the best but it can be made to work.
If you made different plugs/ longer die body you might be able to get the expansion type your after.
The Lee rifle charging die and universal expander die both have 5/8"x 18 threads and I've turned several expanders out of the scrap pieces of soft rod I mentioned a rew posts ago. It works just dandy if you already have the dies and don't have a lathe...but DO have a bench grinder and drill press. I used regular 5/8 fine thread nuts for locking in the spuds.
Brad, 1/2" x 18TPI is a bastard size, you'll have to make the expander and thread it to match and make a jam nut too if that's what you did on the die body. I was suggesting the 1/2x20 because you can just use regular bolts that are already threaded, just whack off the head and turn down the unthreaded shank for your spud. What would REALLY be useful is to make extra-fine threads, like 24 or 28 tpi, for finer adjustment. You could make a nut out of the top 1/4" of the die body (make it that much longer than normal to begin with) and part off the ring and maybe file a couple of flats on it for a wrench.