That wide grooves with narrow lands style rifling was called Forsyth style rifling back in the early 1800’s. Now it did’nt have radius grooves that I know of, but it is known to produce tight groups. Bill Large did some Forsyth style barrels, and they were tack drivers. They do require heavier patching usually.
I’ve always imagined a Forsyth style barrel, with a gain twist. I don’t know how well it would work, or if it would work at all, but it always sounded good to me. Keep us posted on future testing.
Hungry Horse