Yeah the Beaumont-Adams was still official service revolver in 1879, though officers might have privately purchased Webleys - the earlier solid-frame type. FWIW Custer had a pair of RIC Webleys at Little Big Horn.

I do like the later break action Webleys too. Nicely made and feel good in the hand, and the .455 certainly was well proven as a stopper, particularly with some of the bullet designs the Poms developed before the Hague Convention.