You must be a gun nut. 
The revolvers they were carrying were modern (newer) they just were breech loaders.
Can you explain what you mean by breach loader? I am familiar with guns and terminology, but I don’t know that I’ve heard this term applied to a revolver. Do you mean a tip-up or top-break style? If so, I’ve never liked that style of revolver, for some reason.
The Indian agents were carrying something similar to this.
Don’t know what make but I was told the caliber was .32. .32 “what” I don’t know. 32 S&W? 32 H&R Magnum?