There is no such thing as a 2-1/2 frame as we know it in regards to frame sizes on barrel lugs. Any reference to that in a letter or the records are referring to the frame size as measured across the breech balls.

Now that's an interesting gun.

Bill, I came across a couple of mentions of 3 frame 16s when I searched the forum. There was your 28", and I think a DH with longer barrels was mentioned by someone in the same thread as having been seen. I can't search the archive section. This VH is 2.51" across the breach balls, the same as a standard 3 frame.
The lug stamp isn't well defined, but it looks like the bottom half of a 3. I'll include a photo of it when I post pics and measurements tomorrow.

I doubt they would have chambered for brass shells in 2003 but you never know. I would think that would have been noted. At that time, forcing cones were pretty short and abrupt.

:corn::corn::corn:

Photos
 

Here are a few photos of the chamber end of the barrels and the lug. The rim recess is fairly deep. These cheddite hulls go past flush in the chambers. More to follow.

Here is a couple of the left side of the action. What would you like to see?

When I first looked at the empty chamber picture I thought they looked big and somewhat off center due to camera angle. Looking at the second, the shells still look off center in the chamber, and not due so much to viewing angle. Are they lose in the chamber in addition to being deep?

Here is one of the full left side. The letter has the stock at 13.25". Its now 13 1\4" to the end of the wood, and 14 1/4 to the end of the pad. There is no peak inlet and no serial number or grade stamp under the trigger guard.

No, they are tight in the chambers. I think they look a little off center due to the shadow cast by the exposed rim due to the shells seating past the end of the chambers. That was poorly worded. The shadow is cast by the chamber wall when the hull enters past the start of the chamber. That's poorly worded as well, but I hope you understand what i meant.