Re: Polygonal rifling?
I don't have any hands on experience with it,but I had seen polygonal rifling on two muzzleloaders that were manufactured in the early 1800s. They were both 50cal and I would guess used 200-300gr projectiles, but thats just a guess.
I would think that although polygonal rifling may not be new it should be effective, especially in the recommended twist rates. Less shearing of gilding metal should make it easier to clean too.
If you decide to go that route a nice writeup with pics would be appreciated!