In short - no - no reproductions have been made - though there are a lot of fakes out there, since building a Forager's shotgun was a pretty easy thing to do - back when more Civil War parts were available.
The barrels were from .58 Caliber muskets - shortened to 26" and bored to 20 guage, then threaded for the modified Model 1873 receiver.
The breechblock was modified, ejector stud removed, and the stock filled, tapered and shortened.
Add a new brass bead front sight, a trigger bow from a Cadet or Carbine and a forearm screw lug with the screw and washer from the older Sharps Carbine - and 'waa-laa' - a Model 1881 Shotgun was soon on the gun show table - maybe even a 'rare, experimental' one...
In the past, I've owned a couple of 'real' ones - and I've fired them.
Accuracy and pattern-wise - about all you can say is that they're shotguns - but back when they were found at a Frontier Post - game was beyond plentiful and a shotgun could prove most useful, no matter what...
Vaya,
Scouts Out!