I beg to differ: In the first (mounted) photo I'm seeing the large rounded triggerguard of a double action revolver.
Given that the photo was taken in 1886, the most likely gun, in my view, is the Smith & Wesson .32 Double Action Fourth Model revolver. It was made from 1883 - 1909.
I'm also thinking nickel plated finish, pearl grips and up to a 6" barrel.
In the second (dismounted) photo I'm seeing an 1877 Colt Double Action revolver in her right hand.
When enlarged it looks like she is resting her thumb on the characteristic hump of the 1877 backstrap.
It also looks to me like an ejectorless "Sheriff's Model"....
The holstered gun is probably a SAA.