Thanks for comments!
A agree, the figures aren't so detailed. In general, they are usually suffer from the lack of details on master-models.
Detailing comes after, with Hart's painting.
Unfortunately I have no idea in what style those two horsmen were painted, as for we lost traces of this composition in the world of figure making.
Here is another, more recent, Zaporozhye Cossack, made by Hart.
It's not a master model, but a figure ready to be painted. The time spread in between two sculptures is ~ 1 year. I quess, Hart intended to show us a guy , who was told about the captured turkish rider.
In reality, the personage was taken from the Repin's picture "The Zaporozhye Cossacks Writing a Letter to the Turkish Sultan"(1890-91). You can easily find him there.