Harmonics do occur in muzzleloaders. They may be less pronounced in a ML than a modern due to the lower pressures, longer pressure curve and thicker barrel walls, but they are there. At least according to the laws of physics.
As for adjusting to them, of course we do. Barrel harmonics are one of the reasons we tailor the load to the gun.
IronHand
You're right about that, Ironhand
I suspect I was thinking more in terms of shims, bedding, pressure, whatever, on a particular 'sweet spot'.
But, you're spot-on about tailoring the load, in essence, you are in fact determining that 'sweet spot'.
FWIW; I know my own T/C Big Boar .58 shoots much better when I place a a smaller (.45 cal / 0.0012) patch in the channel under the barrel, near the very end, to apply a wee bit of upward pressure....it's much harder to replace the barrel pin, but groups did in fact shrink, with both RB and Conicals.
Still yet, other guns, other calibers, were a simple process of range time and different patch / lube / load experimentation.
So much so that I never felt a need to explore any further.
The fore mentioned T/C is the very reason I felt Harmonics almost had to be present and vary with load variation in Muzzleloaders using BP.
Keep in mind the platform for the .58, is a old re-worked T/C Renegade Stock, with Davis Triggers and a L&R Lock, which also serves as a basis for a .50 -1:26 GM, .54 1-48 T/C, .56 -SB T/C, and the .58 -1:62 T/C barrels, but that 'patch' under the barrel I mentioned earlier only serves it purpose when using the .58...it is never present when using the other barrels, and all the other barrels including the .56 smooth bore is exceptionally accurate up to 50 / 60 yds.
Making that .58 Big Boar shoot to my own expectations was possibly my own greatest challenge in getting any Muzzleloader to shoot well.
And, THAT is what led me to thinking Harmonics, of some nature, surely had to be a factor.
Someone once said, "Only accurate guns are interesting"....and I fully agree, as most of us do.
And we, those who truly love these old guns, will do anything we can to make them accurate, including doing our best to control the Harmonics, no matter how evident Harmonics may be.
And that experience is the very reason I think Ohio Joe just might see a big difference his accuracy....but, we'll see.
Uncle Russ...