Not so fast George, I believe it to be a different set of serial numbers for the 28-ga. guns. We're looking for a BHE .410 on a 4/0-frame, right?
It appears that Larry Baer's in-the-white A-1 Special 28/28/.410 3-bbl. set that sold in a Julia auction and mentioned several times earlier in this thread isn't the only such set reportedly made IF the gun that Geoffroy hopefully shows us is indeed S/N 28-53.
http://jamesdjulia.com/item/2388-386/