.58 cal rifled musket barrel help?

[Brad]

I bought what appeared to be a rough blank for a replica type civil war rifled musket barrel. It was 40" long and had three lands and grooves inside of equal size.
However the outside of the barrel was approx 1-1/2" or bigger and not tapered or finished.
Somehow it appears this "started" barrel made it out into the world.
Anyway I bought it at a gun show for a song. It was so big and heavy noone had any idea what to do with it.
But I have a pal who is a retired machinest and we used his tapering lathe and made a nice round and tapered barrel out of it.
I breeched it and over the last year or so made a nice flintlock rifle out of it.
I assume that since it appears to be a rifled musket barrel it should shoot mimi balls pretty well.
But first I am trying round balls.
I have a mould for .575. These will go down with a thin patch, but its clear they are just too tite.
I have a few Hornady swagged .570 that are a little better, but are also probably too tite.
I just got a few that mic about .564 that I am going to try and see how they work.
My question is?? Does anyone have any experience with these barrels?? What powder load should I use??
I was using 75 Gr 2FFg with the .575 & .570. Sounds great but really kicks and seems like too much powder.
Not really holding a very good group. Maybe about 4" at 25 yds.
I think these CW barrels used 60 Gr with the mini ball as standard.
Just looking for a little help here with this??
Thanks

[Embalmer]

Civil war loads for the .58 and .577 springfield and Enfield rifles was 65 grains ffg, sharps .52cal was 55 grains, and the 69cal was 80. I personally get good results using 60 grains at 300 yards using both springfield and Enfield rifles and 50 grains in my berdan model 1859 sharps rifle. If shooting up to 150 yards I'll bump down to 50-55 grains.

[k arga]

you will need a tight fitting ball and patch to grab that shallow lands and groves .

[Clark Howard]

A round ball requires a much slower rifling twist than a longer, heavier bullet for effective accuracy. Your barrel may be rifled for the Minie. Regards, Clark

[Johnny P]

Round balls shoot well in fast twist shallow groove barrels, but are much easier to shoot with slow twist. The fast twist barrels are more finicky about loads, and a small change in powder charge can make a difference in zero. The slow twist barrels with roundball more typically shoot to the same point of impact with different powder charges.

I shot a Thompson-Center .50 with roundball and 1-48 barrel for a number of years, and it shot very accurate when I found the right patch, ball, and powder charge. I later switched to a Sharon Rifle Barrel Co. .54 with a 1-70 twist, and found it shot just about any charge of powder good.

[mhb]

.58 rifling was 3-grooved with a 1 in 72" pitch. This pitch is perfectly suitable for RB, though the groove depth is a bit shallow. Still, you should be able to find a patch and ball combo that shoots well.
You did not actually say what form or pitch the rifling in this particular barrel have, but most combinations can be made to perform reasonably well with PRB.

mhb - Mike

[Mickey Christian]

What is wrong with a good hollow based minne?
When I shot these rifles we put a dab of Hodgdon spit patch in the base to keep fowling soft thus allowing easy follow on shots....harder to do with a round ball. They are available in various weights.