I really enjoyed the film showing the rifle and talking about its provenance. Great rifle in fabulous shape.
But the author doesn't know much about load development. In his defense, though, it's likely that the bore is not as good as the outside of the barrel, and loading a proper tight combination might have been impossible. In the jaeger that I built, also a .60 calibre, with a 31" Getz barrel having round grooves, I load a pure lead .595" round ball and a .020" denim patch. I too use a short starter, and when target shooting, a 3/8" steel rod - a hickory one when hunting. The rifle loads easily. My rifle also likes a .590" ball and a .030" denim patch. There is no difference in the ease of loading. Also, I use 86 gr. FFg GOEX for my plinking/trail load and 120 gr. for hunting. With these combinations, I can consistently keep all my shots in a five inch bull offhand at 100 yards.
I know we are looking at an original piece, and nor would I subject it to the kind of loads I use in my recreation. It is entirely possible that this rifle's original owner also used light loads, and kept his shots close, and his game small.
It's a nice video, and well worth the look. And it has spurred me to restore the old jaeger I have in my to-do list.
Thanks Kermit.