I’ve been fighting with leading in my 9mm for a while now so I finally decided to pull a couple rounds and see what they measured after they were seated. I found my best luck was sizing them to .358 and it was working OK but I was still getting some leading. I pulled a couple and they measured .355. Ok, so there is my problem, now how do I fix it.
The expander spud on Lee’s 9mm die is really short and measured .353 in diameter. I checked my 38/357 expander and it measured .356 and is much longer. Sooooo, the marbles started rolling around in my head trying to figure out a way to use the 38 expander in the 9mm die. The problem is they are quite different in shape and size. I started taking some measurements and they both have an interior shoulder that sits .430 below the top of the expander that activates the powder measure but the overall length is quite different. So I figure I need an insert to activate the powder measure. Well the insert in Lee’s powder measure riser is a perfect match for this.
I took some measurements and the body on the 9mm expander is 1.197 in length. The body of the 38 expander is .663 in length so I need to make up the difference of .534.
The difference in length needs to be made up in two different ways. One internally for the powder measure and one externally for the expander.
To make up the difference for the activation of the powder measure, I trimmed the riser insert by cutting it off with a dremmel and finishing it with a file to a length of .734. For the powder measure to work correctly the difference has to be made up on the interior where the powder measure tube rests on the shoulder of the insert. The shoulder sits .200 down from the top of the insert so that has to be added to the overall dimension.
For the exterior all I had laying around was some 1/2 inch PVC. The OD of the expanders is a little bit smaller than the OD of the PVC so I had to take it down a bit so it would work. Just my luck 1/2″ PVC fits perfectly in a possom hollow trimmer.
Once I got it sanded down I cut it to length and mocked it all up. It took a few adjustments on the length of the PVC shim but once I got it, everything worked perfectly. I seated a few boolits and they are pulled the same diameter that they were before they were seated and it works the powder measure when expanding the brass.
Having covered the how and why of all this there is an easier way to achieve the same results. The expander body for a 38 S&W is dimensionally identical to the 9mm expander making it a direct drop in replacemnet with the only difference being the expander portion. The expander portion on the 38 S&W piece is the same dimensions as the 357/38 special piece. So for $3 in parts plus shipping you can get a part directly from Lee Precision that will solve the swaging problem.