The back story is of a Lyman Great Plains rifle kit I built in the 1970’s. It had the slow RB twist of either 66-1 or is it 60-1. I knew but don't remember what they are now. It shot RB well enough and soon after I thought I needed a T/C Maxi-ball for it. That rifle shot the maxi-ball very well to 100yds plus and I used it for hunting mule deer and elk here in Colorado.
After who knows how many times it was loaded and shot in 40 plus years and likely not too carefully in the early days, the accuracy dropped off. Sometime about spring of last year I found a drop-in Lyman replacement barrel and installed it. The new barrel is a faster twist. A Hunter barrel I think and maybe it is a 32 twist.
Right off I started with the T/C Maxi-ball and had a great deal of trouble getting any kind of accuracy with it.