Think you nailed it.M1871 Beaumont - Wikipedia
en.m.wikipedia.org
Maybe this.
Too many European battles were decided "at push of pike". Hard to get away from that thinking, even with repeating rifles.They're long with long bayonets to use like lances.
11x50 or .43 Dutch.That round looks sort of .43 Mauser-ish. Cool stuff .
Stay safe.