pamtnman,
I believe the purpose of the oval bore was to lessen problems caused by black powder residue. Several different forms of rifling were for that purpose, some with the rounded lands are sometimes mistakenly thought to be worn out.
Mike
No doubt they started with that stated goal, and marketed with that purpose, but it does operate totally differently than conventional rifling. And my experience owning and shooting several oval bore rifles from the 1880s, 1890s, 1910s is Im not convinced its really a cleaning / non fouling advantage over conventional rifling. Its actually more difficult to clean because the oval bore creates shallow pockets where fouling collects. Requires many many passes with really big brushes, lots of big wet rags. More than the conventional rifling BP guns i shoot.
Anyhow, Im analyzing the antique 450/400 3-1/4 rounds that arrived today. Right now just aggregating exterior measurements. The average OAL of both the Eley 1880s paper patched and the Kynoch early 1900s-1910s NFB rounds is 3.8, much longer than shown in the old Kynoch catalogue and which I had seen elsewhere.
