FWIW:
I admit to trying this sometime back in the early 70"s. In fact, I was with the Paso Del Norte Muzzleloaders, in El Paso, TX.
Back in those days the Mexicans could bring their Muzzleloaders across the border and participate in our version of a Silhouette Match.
During one particular match, a Mexican shooter showed up with these sewn patch balls, and everyone was practically dumbfounded....This particular shooter took a lot of time, I have to imagine, in putting that patch on those balls!
I also definitely remember that he was a good, probably even great, shooter.
Our only rules for participating in those matches were, open sights, no peeps, and no scope.
I clearly remember his rifle had a rough cut, obviously handmade, "Silhouette" sight...it was a slide blade type, much like that found on the Winchester 94 of those days, that had four notches zeroed in elevation for 50, 75, 100, and 125yds....he had obviously spent some time adjusting / filing that sight for those elevations while using pattern after pattern to get it right!
Nobody ever knew for sure if that sight was his secret, or if it was the sewn patch on the roundball. But he was clearly a hero for that day.
He shot an honest 19 out of 20, with a hit on a Ram that didn't fall over...otherwise he would have had a perfect score. Likely the highest score ever shot on that range with a Muzzleloader.
Was it in his fancy patch, his sight, or his skill?
My guess is it was in his skill, although that sight surely helped.
So, after that match, everybody had to give those patches a try...myself included.
To me, they were easy enough to put on, although nothing fancy like the ones he had put together.
But, if they ever did anything, other than possibly a wee bit of convenience, I was not smart enough to see it.
Like all the others, I went back to my old ball board, and that's where I stayed.
(A few years later, after I had retired from the Army, I inquired about that fellow, and although everyone knew who I was talking about nobody seem to know where he was or how I could get in touch with him....I got to thinking he was on to something with that sight, and I had hoped we could do a little business together.)
Uncle Russ...