So, enlighten me…(about historicity of short starters)

[Longknife]

Those  long coning tools that have been marketed were developed without much research. Every cone that I have inspected wasn't that long, or deep into the bore. The universal coning tool I make produces a very short cone, all you need to do is remove enough of the rifling to be able to thumb start a patched ball' Here is an example done by a customer. You can almost see where the cone ends. I usually don't even remove this much rifling but the owner claims it works great!

[Daryl]

I see that one is likely 1/2" deep, Ed.
This one is less than 1/16" deep and easily forms the ball and patch into the bore.
No thumb start, of course.

[alacran]

First off, I don't see the need to cone a barrel more than Daryl's patented thumb crown smoothing.
What is the point of thumb starting?  Speed of loading? Speed with muzzleloaders is an oxymoron. If you want a quick second shot for hunting, carry a pistol of adequate caliber and learn to use it.

[Daryl]

If speed is a requisite, then a paper ctg. is the method. With mine(14bore), I was able to fire an aimed shot, 8 seconds after the first shot.
It took some practice, but was entirely dependable. The design of the rifle is of paramount importance in fast aiming.  I carried paper ctgs,
in my right parka pocket, with the capper in the left breast pocket. The average American styled rifle is not designed for this fast shooting.
The various early guns which resemble Germanic heritage, are better for this than the later designs.

[Jakob]

CapAndBall did a video on Napoleonic skirmishers and they appeared to have starters?
https://youtu.be/wrhRT9yx4YE?si=TU2lTQXKsSHEvCXk&t=794
Not sure how accurate this is.

[alacran]

I just watched the video Jakob. Thanks for posting.
It appears the starter is used as a mallet to seat the ball. A few ball blocks would have really come in handy.

[Pukka Bundook]

British Rifle regiments were issued a mallet to so many men, or every other man, I forget.
This was for when something got stuck, not for normal use.

It was there if needed was all.

Best,
Rich.