Sometimes.
It's common for westerns to have anachronistic guns. The anachronisms in Westerns don't really bother me, I just point out that it's an anachronism afterwards. I'm just more impressed when they are using more period correct firearms. Personally I think they could make some more cap and ball revolvers in shootouts. I think it could definitely add to the drama with struggling to reload quickly. The Ned Kelly movie too didn't bother me with the whole gang having helmets rather than just Ned.
The interesting thing is that some minor things really do annoy me tho.
Sherlock Holmes: A Game of ShadowsThe use of the current German flag instead of the period correct one. Seems like something one would think they'd get correct. Like I don't expect to see 50 stars on a union flag in cowboy movies and they don't do that.
I bought a massive multipart Documentary about the First World War with an American Narrator (I don't recall the name of the doco or the bloke). He mispronounced
Schlieffen Plan. How am I supposed to have faith in the doco if you can even get that right. I returned it the next day.
