Lubing the grooves is the period-correct way of lubing, too. I have heard N-SSA folks say they have recovered base-lubed balls and found lube still in them, and there was some concern that the lube might alter the balance of the ball and thus harm accuracy. Who knows?
I have not found any of the traditional minnie ball styles to shoot well in my 1:72 twist Enfield. The RCBS Hodgdon "skirmisher" bullet does much better. Not an authentic bullet style, but it has a large rear grease groove that holds much more lube than a traditional minnie. You can tell a difference in shooting them in how much longer it stays easier to load, and of course accuracy is better.