I don't think you understand what I meant, maybe I did not explain it well.
The standard dies are threaded 7/8"-14. If the press itself is threaded for standard dies, then there is no way that you can install a breechlock insert. The two sizes available for the breechlock inserts are 1-1/4"-12, or 1-1/2"-12. The press MUST be threaded those sizes for the breechlock insert to work. Presses that are threaded those sizes come with a reducer installed, which is threaded internally to the normal 7/8"-14 so that normal dies can be used. Here is a photo with the reducer in an RCBS press:
View attachment 942346
Not all presses have those reducers, the press itself is threaded 7/8"-14.
Midway DOES say something about reducer bushings, since you have to order the correct size for the press you have, namely 1-1/4"-12 or 1-1/2"-12.
And I will note that this list is NOT comprehensive, I know for a fact that the RCBS Summit press has a reducer in it, since I had installed a Hornady bushing insert kit on the one I had.
So, Lee does mention it, although they call them "removable press bushing/adapter" where I called them reducers. Same thing.