That definitely does not match what I'm measuring, on anything except actual small base dies (not Hornady). All my other dies including Hornady don't size the base diameter very much (less than .001") on minimum spec chambers, because it's not needed. However, some size the shoulder diameter more than others, and Hornady dies are one of those, in most cases sizing the shoulder diameter .004"-.006" smaller, compared to Forster and others at only .002"-.004" depending on the cartridge. Interestingly, the Lee dies I'm measuring (including my 6 PPC dies which work for the 6 ARC and other 6mm Grendel-based wildcats) size the shoulder diameter less than Hornady and are closer to Forster dimensions. That Lee 6 PPC FL size die actually works very well for my 243 LBC chambers, matching the body dimensions closely.
When I say shoulder diameter, I'm referring to the body diameter at the shoulder/body junction, just using fewer words.
Based on that, I don't consider Hornady dies to be small base dies like what RCBS makes. IMO true small base dies that size the base diameter down more than needed for most chambers are a detriment to accuracy. I've achieved very good accuracy with Hornady dies though, if care is put into getting low rounout and adjusting dies to match the shoulder datum dimension in the chamber.
YMMV.