Good advice for sure…Shooting & Loading Opinions Galore !!!
I knew nothing when I started shooting & collecting antique firearms as a young history buff.
Six plus decades of active study & collecting, competing & hunting with a wide variety of primarily original English & European flint & percussion firearms developed by the worlds master gunmakers who set world records for long range accuracy,, they taught the world about any successes in accuracy we achieve today.
Early master English & European gunmakers who immigrated to America's colonies taught most of our early gunakers how to build.
*The vast majority of the large bore rifled long guns i've owned & competed that were developed to shoot patched round balls usually feature rifling with one turn in length of the barrel & the rifling depth has varied from .012 to .018 deep.
The above large bore rifles generally had 2-3 leaf rear sights & required powder charges of approximately 80 gr of 2F to provide exceptional long range accuracy.
Everyone has their favorite style & period firearm. I tended to gravitate mostly to big bore Jaegers & English & French sporting rifle & pistols because of their quality workmanship, light weight & unbeatable accuracy if I loaded properly & did my part.
Rifling depth is usually deeper in all earlier vintage PRB firearms, I suspect to utilize the thicker fabrics mfg of that era or use of buckskin as patching material.
I have recovered original flint & percussion era round ball firearms that were still loaded with buckskin used as patching.
* Early firearms that were designed to primarily shoot projectiles generally featured much shallower depth rifling with a faster twist.
The rifling depth & rate of twist on Whitworth & belted ball rifles I've owned & shot are exceptions.
** Powder charges:
Almost without exception all of the above 'original' rifles including the Whitworth were designed to require much less of a powder charge to obtain suburb long range accuracy.
Most of the original larger bore Hawken rifles I've observed & fired have had rifling around .012 deep & featured one in 48" twist rifling.
CHALLENGE;
During the 60s-80s while having a muzzleloading storefront I taught muzzleloading to improve accuracy & hopefully increase sales in my area..
Many newer shooters during these years were using huge powder charges with their .45 & .50 cal. rifles in the area of 120 grains & getting poor accuracy. Maybe due to watching the big bang overloads used in frontier movies ?
At the range I would have them fire their overcharged rifles over approximately 40 feet of white butcher paper. the unburned powder, poor hits on the target & shredded patches demonstrated how much powder they were wasting.
At that point most were open to learning how to determine proper powder charges & the right patched round ball combo to insure better accuracy.
None of the above info is new to those who have also learned from the history of the worlds master gun builders.
Relic shooter,, at 81 I'm now a relic
Also during those same 60s-80s, Lt James Forsyth’s 1867 book “The Sporting Rifle and Its Projectiles“ magically reappeared and circulated amongst us muzzleloader fanatics.
The highlights of his book ( written from his extensive African/Indian dangerous big game hunting experiences) emphatically endorsed the use of:
1) Round balls instead of conical bullets
2) Very slow twist pitched deepcut rifling 1:75 twist
3) Larger caliber bores
4) Large charges of powder with durable patching and over powder wads or patches.
Sam Fadala in the 80s wrote about how well this worked…I too can vouch for James Forsyth’s ballistic ideas…
My serious hunting guns are .54 cal 1:75“or 72” Getz deep round bottom rifling barrels….pretty much take all the powder you can endure while maintaining accuracy…
Around 130 grains (volume) unburned powder is flying and recoil picks up…but the accuracy remains, trajectory is flat and substantial authority is delivered out to about 130 yds…
None of my Thomson/Cabela/CVA “Hawken “ fakes were ever able to take more than 60 grs of powder with out losing all semblance of accuracy….just some more information for the OP to digest.