I didn't know that "traditional" was synonymous with precivil war. But be that as it may, Roberts first book does a fairly good job of discussing the evolution of firearms in the latter half of the 19th century, when firearms were changing faster than they ever had before or since.
I also think that there is a fair was a fair bit of knowledge about bullets during the 1860-1880 time period, where you seem to be most conflicted.
In 1874 John Rigby and crew brought their muzzleloaders (mostly .45 calibers) and 500+ gr bullets to Creedmoor NY for the single most famous rifle match in history. They didn't invent that technology the night before they arrived either.
I am not much of a historian where it comes to the Civil War. But there are quite a few accounts of long range shooting using Whitworth and other rifles, purpose built for long range work. They too, were not invented overnight but certainly existed before the war to some degree.
So, ballistically, my rifle was certainly well within the "traditional" period - at least as you seem to define it. The Hopkins and Allen underhammer had not been invented then although trigger-guard mainsprings and near identical mechanisms were old news (see the post on the Kendal underhammers in the gun building forum - gorgeous rifles!).
http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/229646/tp/1/
Anyway, what's done is done, and I worked pretty hard to figure out how to make it happen. It took a bit of history and a bit building skill, and a bit of bullet development and a lot of practice. So, I got what I wanted out of it.
I currently have a half built, Alex Henry style of muzzleloader that will also be .45 caliber, will also be fast twist, long range bullet rifle. To disqualify an Alex Henry or a John Rigby or a Whitworth as a traditional rifle seems pretty ridiculous to me but perhaps some of you do. In any event researching what is required to build one, and shoot effectively is a lot of fun for me and a lot of other folks that I know.
Brent