They are talking about the RATE of twist - how many inches of barrel is required for the rifling to make a complete revolution.
: IT matters not how may grooves there are. Normally, there are 6 to 8 grooves.
: The faster twist barrels, ie: 1 complete turn in 32" of barrel, are designed for shooting elongated bullet-type projectiles - conicals, slugs, whatever and generally shoot poorly with patched round balls at high velocity.
: Slow rifling-twist barrels, ie: 1 turn in 66" of barrel, are designed for patched round balls, not slugs or elongated bullets.
: This has ABSOLUTELY NOTHING to do with twisted-steel barrels as these are techniques for making damascus(welded) barrels, not the rifling itself.
: I suggest you buy a bunch of BP digests and start learning. Without a basis on knowledge, it is difficult to help you very much. You must have a basic understanding of what rifles are & the dynamics of how they function.