Just noticed a sales thread referring to .22 hornet brass being "fire formed" down to .17 hornet

Now I know about fire forming to increase capacity, I own a K hornet so all my brass has been fire formed, but surely you cant "fire form" down in calibre because there's no way the larger starting calibre will fit the smaller calibre breach & barrel,

or is it just referring to brass that was neck sized down to drop the cal first, then after being necked has been fired ? in which case it should be called "once fired - neck sized" brass, or just plain "neck sized"