Saddlesore, TC did only recommenced pure lead, but not because it would "wear out" a barrel. It was because their barrels were rifled only .003" deep and hard lead would cut patches because they had to be thin. So many people complained that the hard balls would not shoot well. Hence the recommendation.
For years Green Mountain made drop-in conversions barrels for the TC rifles for that exact reason. But no more unfortunately.
What Randy did was to put a lubed patch on top of the powder as a wad. His gun just had the standard TC barrel, but he got excellent accuracy with hard balls and 95 Gr of 3F. The wad cushioned the patched ball in front of it, well enough that he good good accuracy. It's a trick I have also used at times with deep rifled barrels and it really does make the guns a bit more accurate if you run large charges. Not every gun, but a lot of them.
The barrels I use on my round ball rifles have grooves cut from .009 to .0012 deep so you can use thick patching. It makes for much easier loading with hard balls because a patch of .016 to .019 is a LOT easier to compress then a patch only .006 to .008.
There is just more cloth to use, so it gives a better cushion and a thicker "gasket".
In my experience with making muzzleloaders, if you have a clean barrel of any quality, and you are not getting good accuracy, 19 time in 20 the problem is the patch,and/or lube, not the gun.
