The huntsman.58 is an extremely accurate rifle with both roundball and Minnie’s. That’s a fine group you have there for sure. And I’m pretty sure your 1:56 is correct if I remember right.
Yes, most all reasonably well made muzzleloaders, old or new, as long as they have a good bore usually hide a significant potential for accuracy that many shooters fail to completely explore. I was one of those shooters from the early days of the muzzleloader revival of the late 60s early 70s.
Over the years I've run full circle with muzzleloading firearms, including the hottest gadgetry of the 777 and three pellet modern inlines. Also along the way experimenting with all forms of projectiles and tricks. Contrasting, a good slow twist rifle is something to behold with a properly loaded patched roundball. After a few years of exploring the nuances of all the "modern" guns, projectiles and all the various substitute powders, I sold all that or traded it down the river.
Now I only have a modern 54 cal Hawken replica with all correct, custom parts, I built back in the early 70- a dedicated patched roundball rifle. I only shoot real BP. My greatest interest and love revolves around good condition, shootable, original muzzleloaders of the Mexican War to Civil War era. But I also shoot and tinker around those edges with some earlier rifles, a couple in original flintlock configuration.
It was during my dedicated historical anachronisms with these original rifle muskets, I discovered the true potential of most of them. With a lot of reading and a lot of trial and error, I learned the secrets for accurate Minie shooting. I also discovered the hunting potential of a soft lead Minie traveling at their original modest velocities loaded over modest charges of real blackpowder. One of the most impressive was a penetration test of a pure lead 69 caliber Minie into the standard, tough media I use for all such testing including premium jacketed high vel bullets out of high powered cartridge rifles. Even though the impact velocity was only 950-1000 fps, that 69 caliber Minie out penetrated most all premium high powered expanding bullets. Simply put (my theory anyway), it didn't waste much on kinetic energy deformation and transfer to the media and used all its momentum for penetration with very little deformation. I shoot three different 69 caliber originals but only have one suitable for Minie shooting- an original M1863 Plymouth rifle. That test had one of the most surprising results of all the muzzleloader media tests I've done. Once I learned the secrets of shooting the Minie, I would not hesitate to use any of my Minie rifles- 54, 58 and 69 calibers for any big game at reasonable ranges here or for any PG in Africa.
And back to Bob's story about his surprise tooth filling removal exercise, absolutely.... they can recoil more than a smidge!
After all BP is not only pushing a projectile out the muzzle but also pushing a good percentage of its own mass out the muzzle. I've owned (and sold after short relationships) a couple of the 54 cal TC Renegades. I learned their stock ergonomics off the bench don't exactly lend to recoil mitigation
Load a 420 gr conical over a stout charge of BP, hunker down on a bench and enjoy! I still shiver and shake my head at Selous' account of the double charge shot with his Hollis 4 bore. Those were loaded out of a leather bag of powder by scooping up a handful of BP powder (most estimate the average at about 410 grs), charging the bore by hand then ramming a 1750 gr lead roundball down on top. Selous, in the heat of the moment during an elephant hunt, not realizing his gun was already loaded, had his tracker load another full charge of a handful (400 + gr) of powder followed by a 1750 gr roundball on top. That is a 400 + gr plus charge of BP under at least 3900 grs of 2 balls and powder! At the shot the stock splintered (a stock that was wrapped with rawhide to prevent breakage) leaving a deep wound under his jaw. Splinters of the stock and barrel flipped upward and to the rear while flipping him backwards. He also recounts that he was surprised the barrel didn't burst. ooohhha!
