Poprivit, The "bar in wood" phrase refers to the bar of the action being fully let into the same piece of wood as the buttstock (in a similar fashion as a muzzle loading double) as apposed to the stock wood stopping at the rear of the action. I don't know when this style of stocking gave way to the "modern" style of stocking but it seems like it was a specialty of Westley Richards'.

The Westley site puts your gun at 1872

http://www.westleyrichards.co.uk/THE-COMPANY/Gun-Histories/History-Authentication

BTW, there is this example for sale at Cabelas:
http://www.cabelas.com/gun-inventory---ft-worth---english-sg---882282-wesley-fw.shtml

Notice the difference in the positioning of the firing pins and the way the hammers are shaped for the centerfire only configuration. You should call Cabelas and get a serial number for this one - bet it is just a couple years after yours - still bar in wood, but abandoning the pinfire option.