Who can answer why ....

[Road_Clam]

Lets see who know's their muzzleloaders. The .58 cal Minni's on the left were shooting about 18" low at 50 yds . The ones on the right were shooting dead on at 50 yds , both weigh the same, casted with the same mould , 40 gr of FFFG Goex and sized to .578 . (I did eventually figure this out but I was really scratching my head at first !

 

[38ExtraSpecial]

Lets see who know's their muzzleloaders. The .58 cal Minni's on the left were shooting about 18" low at 50 yds . The ones on the right were shooting dead on at 50 yds , both weigh the same, casted with the same mould , 40 gr of FFFG Goex and sized to .578 . (I did eventually figure this out but I was really scratching my head at first !



View attachment 755582

Different alloys?

 

[FPrice]

The ones on the right look...shinyer. Something about the alloy or the finish? The "duller" ones on the left created a tiny bit more friction, slowing them down?

That's my SWAG

Scientific Wild Assed Guess

 

[Arto]

Hardness?

 

[Road_Clam]

Hardness?

You would be correct ! For . 58 Minni's to shoot with any good accuracy you need to size . 001-.002 under bore so they can just barely slide down the bore . The base skirt needs to expand from the gasses and seal against the bore. Minni's need to be casted from pure lead. Pure lead is about a 5 or 6 on the bhn scale and i must have mislabled some of my harder lead ingots and tossed them into my pot (i test my ingots with my Cabin Tree tester and mark the hardness with a Sharpie) . I casted about 40 bullets and the the hardness was up around 9
bhn . No skirt expansion = gas blowby = mouse fart velocities which ultimately was 18" low poi at 50 yds. I kinda laughed in hindsight , what a bonehead mistake .

 

[magoo]

Did you run a patch after each shot. Sometimes the build up of lube and black powder residue makes it so bullet does not in gauge rifling.

 

[gerrycaruso]

The first thing I thought of was composition but you said they weighed the same. Shouldn't an alloy bullet be lighter and harder than a pure lead one?

 

[dhuze]

The first thing I saw when I looked at the picture was 2 of those look heavier than the other 2.

 

[Maxrobot]

Serious Minie ball target shooters fill the hollow base with Crisco shortening. It helps the base expand and keeps the powder fouling soft so you can fire more shots.
it looks like you swage the Mini's after casting. What do you swage them to? What are you shooting them from?