I had two longrifles built using Getz barrels with round bottom grooves, and factory coned muzzles. Both were flintlocks, with hand assembled large Siler locks. One in .50 caliber, and one in .62 caliber. I ordered both barrels with 1:48" rates of twist.
Both barrels shot extremely accurately out to 100 yards on targets. With my lousy eyesight, offhand, at 100 yards, on any given day, aged 25-47, I could expect a 4"-5", 5-shot group. In the hands of a good offhand shooter with excellent eyesight, both of the barrels were capable of putting 5 shots under a 50 cent piece at 100 yards.
From a bench, which I seldom shot from, both barrels could keep 5 shots under 1" at 50 yards, all day long. Most of the time, 5 shots looked like one ragged hole, if the bench shooter was doing their part.
Ball diameter for both barrels was 0.005" under bore diameter. Patch material was thick enough, I never measured its thickness, to completely fill the grooves, imprint the weave of the material into the lead ball, and push 99.9999% of the spent fouling down onto the new powder charge when seating the new patched ball. This allowed multiple repeat shots, ad infinitum, without needing to ever clean the barrel.
For shooting targets, the powder charge for the .50 caliber barrel was 70 grains of fffg black powder by volume; and for the .62 caliber barrel it was 75 grains of fffg black powder by volume.
If I had hunted back in those days, I would have had no issues using those powder charges/balls/patch material combinations to deer hunt with. Only thing needing changed would have been moving to an animal-based lube, instead of spit.