I do not know. I have seating dies, one of them is a Dillon 45 ACP, I guess I could call it ‘Guffey’s Dillon seating die. It would help if I knew where your information came from. You could start with ‘I was at the pool hall when I heard someone talking about it’.
The die I use depends on how I am loading. If I am using a RL550B Dillon I seat and crimp on one position, I have the option of seating on the 550 and crimping after. There are times I use a carbide sizing die for crimping.
I was reading a thread on reloading here on the firing line, and someone said to get a Steve's dillon seating die, when I went to the site they mentioned, I couldn't find the die listed, so I joined this web site so I could ask where to buy one.
I don’t know where the Steve’s part comes from. I think Steve Dillon is the engineer responsible for Dillon’s Gatling gun project. Mike Dillon, who I think is Steve’s father, started Dillon Precision. But that is just what I heard.
Well, darn.
I hoped Steve had come out with an adjustable Dillon seating die. Trying to fine tune OAL by turning the die body in sloppy 7/8x14 threads is very tedious. The quick removable seating plug is not worth it for me.
I use a Hornady .45 seating die with micrometer adjustment on the Dillon press.
My 9mm Dillon die is left at a compromise setting that works for most of the bullets I load in the caliber. I only have to tinker with it to load hollowpoints.