This view shows some of the basic features of this saddle.  The tree or rawhide-covered seat appears to be a genuine CW era saddletree.  That's where the Civil War ends and the "post-CW" begins.  Note the skirts are only held on with about 1/2 the regulation number of  screws, arranged in a single row, instead of the normal double row.  The saddlerings are held with round wire staples, instead of the usual CW pattern flat iron staples, a post-CW period condition.  If you look at the stitching holding the quarterstraps to the dee ring, you'll note the one-piece "pointed" shape - this indicates machine work, and is typical of late 19th century saddlery.   The stirrups are typical late 19th century/early 20th century wood.

Note the position of the "Alleghany Arsenal" plate - these are usually located much closer to the quarterstrap, or even slightly underneath it.  From the looks of it, this plate was taken from another saddle (note the wear mark?  indicative of quarterstrap wear if in a more likely location) and placed on this one to cover up the original staple holes.   You can just see the edge of one peeking out at the top.  You can see where the replacement rear ring is located in the post 1885 position, under the cantle foot staple. 

Here's another nice view, that shows odd placement of arsenal id plate, single line of skirt screws.   There are no saddlebag staples on the rear quarterstraps, or any indication that there were ever any there.  No saddlebag stud.  This all indicates that the quarterstraps and skirts are post-CW period replacements.