To my limited knowledge, the "break-top" wheelguns were in use often with the UK's armed forces. I think the Webley .455 sidearm was issued to army officers & mounted(horse) troops.
If I recall, Dr. Henry Jones; aka: Indiana packed a big break-top revolver in the third adventure film. I may check www.imfdb.org
or the special Indiana Jones film gear-weapons fan website.
BTW: any forum members know what kind of break-top revolver Keith Richards uses in the old Rolling Stones music video for "Undercover"?
I know it's an 80s era video but the big revolver looks like a 1800s era military sidearm. A .44 or maybe a .455 caliber.