I shot each with 60grains 3F Goex
I will say this, the .585 mb was noticeably harder to push down the first inch or so till it grooved the minie. Your .575? and the .580 were pretty much on par with each other as far as ease of loading.
Targets are:
Upper Rt : Lee .575/500 mold. They were sized to .575; lubed with a 50/50 mixture of beeswax & Crisco
Lower Left : Track of the Wolf .580 lubed with bore butter
Lower Right : Track of the Wolf .585 lubed with bore butter
Ok, in that case try a Minie with a thinner skirt, if they still make them. Also, Lee used to make a mold for what was called a "flying ashcan." Some of my buds shooting original rifled muskets had good results with them. Maybe TOW or someone from NSSA still makes them.
With a trigger that heavy, I am surprised that you did this well.
Apparently the tighter the rifling engagement, the tighter the group:
.575 had 3.686 MOA mean radius.580 had 3.320 MOA.585 had 2.167 MOA
View attachment 229854
View attachment 229855
View attachment 229856
What app are you using to capture the measurements on your pictures?
I am using OnTarget ‘Precision Calculator, version 2.25.
Input to the program is with photos that I take of the targets; processing is with mouse clicks; the program does the rest. You can save program specific results or .jpg views.
4570inMD
One thing about Minies is that pure lead is not optimum for making them. Because the skirt expands on firing, they can be blown out as it clears the muzzle if it is too soft. I forget the alloy I used when I shot civil war rifles but you can find it easy enough by googling.
I'm thinking 3% antimony will do the trick.