Hello my question is what would the velocity gain/loss be if I choose the 62 caliber (.610 -345 grains) vs the(.600 - 325 grain ) round balls. I am finding it easier to find the .600 round ball than I am with the larger one, and I’m kinda curious about it too. I shoot a 62 caliber Leman flintlock with a 36 inch custom made rice barrel 1 1/8 inch across the flats and 1:72 twist. It shoots the 345’s really good with charges from 95 grain to 150 grains Swiss 2FG. And can kill a giant possibly too.
Thanks in advance
Don
Are you talking about bullet moulds to cast your own, or balls that someone else has cast for you?
Your best accuracy will always come from a tightly patched ball measuring 0.005" smaller than your barrels bore. It will REQUIRE a short starter.
In the case of a modern .62 caliber Rice barrel that will be a ball measuring 0.615" in diameter.
Back in the late '80's, when I had a Getz barrel in .62 caliber the only mold I could find was a Dixie Gun Works iron mold in 0.610" diameter.
I never had a mold for round balls for any of my rifles that had a sprue plate. I had to cut the sprues off with a pair of dikes.
Round ball barrels are very forgiving, and can be made to shoot very accurately with a variety of patch thickness/ball diameter/powder charge combinations.
Depending upon what YOU ARE LOOKING FOR, stellar accuracy will probably come from only a single combination of the above.
IF YOU ARE NOT CASTING YOUR OWN BALLS..........
I would invest in a Lee .610" ball mold, a simple cast iron dutch oven that will hold at least 20 pounds of melted lead comfortably, a lead thermometer from Rotometals (best price), a Rowell #1 bottom pour ladle from Rotometals, some form of skimmer that is perforated, a hickory hammer handle to bump the sprue plate, and a digital scale to check the fill weight of your castings.
This is all one needs for patched ball casting. You can spend more, but for me I like the simplicity of casting balls.
You still need to pay attention to the details so that the mold's cavity is completely filled out with each pour. The thermometer to keep the lead at an even temperature, and the Rowell #1 bottom pour ladle with its 1 pound lead capacity will almost insure that each ball is as perfect as the last one.
As far as the differences between the 2 weights of balls and velocity losses, you should be able to adjust the powder charge to compensate.
The .600 ball in the .62 caliber bore is going to require such a thick patch that finding the material may be difficult. If your Rice barrel has 0.016" deep round bottom grooves then here is the math.
.
0.620" bore + 0.016" + 0.016" = 0.652" groove diameter
0.652" groove diameter - 0.600" ball diameter =. 0.052"
Just to seal the grooves you would need a material that tightly compressed in a micrometer or caliper that measures 0.026" thick.
To tightly imprint into the ball for decent accuracy the material will have to be a minimum of 0.030"-0.032" thick
Material that thick is hard to find. Probably be heavy cotton canvas.
