I thought of something else. Not all 38/357 Magnum die sets will load the longer rounds. I had my original set of RCBS from the early 1970's, as well as the Dillon's I load my 38 ammo in quantity with on my Dillon 550. Correction the RCBS were my second set of dies, as they are carbide. I gave the non carbide dies away when the RCBS carbide dies came out.
The older RCBS carbides would not work.
The Dillon's will not load 357 Maximum either.
I ended up finding a set of used RCBS Dies that would load 357 Maximum at my local Pawn & Gun. I also found a Taper Crimp Die while doing my search for dies. Just for another loading option, not required.
The point being, if you have been loading 38 Special/357 Magnum forever your dies may not be new enough to load 357 Maximum.
See You At The Range