Question about an old Spanish pistol

[doncameron]

looks like a S&W the only markings are as follows
32/20 US Service CTGS on the side of the barrell,
Garataenitua & Cia (ESPANA) on top of the barrell,
SN # 477XX on the bottom of grip frame,
924 inside the cylinder latch hinge and under the ejector.

It belongs to a co-worker and he is interested in when it was built and is ammo available for the pistol.

 

[Radagast]

32-20 ammunition is available, loaded for use in old lever action rifles.
http://www.winchester.com/products/...x?symbol=X32201&cart=MzItMjAgV2luY2hlc3Rlcg==

or for cowboy shooting:
http://www.ows-ammo.com/catalog/product_info.php/cPath/21/products_id/662

If your friend really wants to find out he can buy a reference book:
https://www.alibris.com/search/book...s: The History of Spanish Pistols & Revolvers

Beyond that, all I can say is that a large number of small manufacturers made various near copied of S&W revolvers in Spain prior to, after and during WWI, and your friends gun is probably one of them.