I could go back with the concept of modern bullets and breech loading rifles on the American frontier. It seems to me the concept would be achievable in those times. Tell me I'm wrong and I'm willing to listen.

Define when you mean as the American frontier. Considering that as soon as such weapons were developed they were taken to the U.S. frontier, you can't really complain much. The introduction had to await the development of percussion caps (and eventually primers). In the 1840s Colt introduced his revolvers, and those were effectively breech loaded after a fashion. Anything substancially better had to await the development of metallic cartridges with primers. That pushes us up to the 1860s.


buzzard

I rather think the Romans or Byzantines could have implemented Bessimer steel processing. Now granted, this process doesn't produce the greatest steel (hence it not being used), but compared to the steel of that era, it would be world shaking.

You'd probably also want to throw in the steam engine since it is this, and good metal which did much to make the industrial revolution possible.

buzzard

I'd introduce simple generator technology to Egyptians.  They had natural magnets, they had copper, teach them how to make simple coils, then they could make arc furnaces for steel as well as lighting.

My definition of the American frontier has to involve what I was thinking of at the time, and that was when the French, English, and Spanish first came over, a good deal of time before the 1860s. I'm not really complaining, it was just a thought experiment by someone not intimately familiar with the technical jargon of firearm construction and evolution.