problems w/ Minie cast bullets

[tangodown]

I need some help from the collective wisdom of the group. I cast sixteen or so Minie balls last weekend in anticipation of the muzzle loading season here in North Carolina. Only three bullets arrived at the nominal .575; Six bullets at .577; and, the remaining seven (!) bullets at .580... which I have real trouble sizing down to nominal dimensions...

What could be happening here? What are the variables that could be pushing me so far out of spec?

[docone31]

We are missing some information here.
How hot was the melt, or mold?
What alloy?
What time of day?
What was the humidity?
What colour was the room?
Who made the mold?
Lots of factors that could affect casting.
Sometimes, nothing more frustrating.

[oldhickory]

Use either pure lead, or as close as you can get. Burton boolits, (Minies) should be soft enough so you can deform the skirt with thumb and index finger pressure when cold.

You need soft lead, and a mold up to temp. for good hollow base boolits. I don't bottom pour, but if you are trying to get good .58 boolits bottom pouring, try ladle casting them. I tried bottom pouring .58s once, and it really didn't work out.

[405]

Unless you are trying to set velocity/pressure records with the load, then near pure lead is what you should be using. Most minies are big hunks of lead and don't need velocity for clean killing- they need accurate bullet placement. I use pure lead with a smidge of tin for all my conical ML bullets. I've noticed that with the skirted minies, many time they drop from the mold with the skirt out of round by a few thous. I think that is normal, as all castings don't release from each mold half equally. That tiny bit of difference probably causes the skirt to deform a little. With the soft alloy and the soft skirt that flares to bore-fill at firing anyway, I've never had slightly out-of-round skirts cause a problem with loading or accurate shooting of a minie.

Out of round or under/over sized minies that have really thick skirts, no skirts or are of hard alloy.... that is a different kettle of fish. But, the first thing to try is near pure lead with maybe a little tin and to make sure that the mating surfaces of the mold blocks are staying clean. The smallest bits of lead or debris between them can cause the "Beagling" effect.... thus variable diameters of the castings.

[cwskirmisher]

What is your bore size? If the largest of the group will still slide down the barrel, then you really have no worries if they are close to pure lead. Lube them, load them and shoot them. The minor variance in as-cast diameter in a minie disappear when you pull the trigger, as they will all obturate to the groove diameter anyway. If they will not fit in your tube, that is easily remedied by usung a push-thru sizer of your diameter of choice (sounds like .575). If you are having "real trouble" sizing down from .580 to .575 then you are using an alloy that is too hard. Push-through type Sizers are available from many sutlers on the N-SSA site for about $15-$20.

[masscaster]

Hi tangodown & welcome to the site!!

Casting Minie's can be a pain at times, even for me.
First, as stated above use Pure Lead. A touch of Tin won't hurt, Say to 80:1 will help, especially with the larger 450 gr. + Minies.
Secondly, make sure your Lead is HOT. 850 - 950 is a good temp.
Third, run the mould a little fast at first, even if preheated. Don't stop and look at the boolits. This is where the sorting part comes in. Rythmn is key.
Try this:
Get everything up to Temp...,
Close the Mould... And insert the Base Plug.
Close the Sprue cutter with a gloved finger......,
Use your Mallet and gently TAP on the handle at the mould.
Make sure the pin is still in place and pour. Always put the pin in first.
Repeat............... : )
I use a botton pour pot to cast thousands of Minies, with no ill effects. The occasional gas hole, which is usually from not holding the mould at the proper tilt, or the lead flowing to slowly.
Make sure the distance from your spout is just enough to get the sprue cutter screw under also. This is the perfect distance.
Alot of people make the mistake pf pouring the stream at to long a drop. The closer the better!!
If you start getting some extra lead at the base *base finning, or seam finning, slow your lead pour rate until this dissapears.
Feel free to PM with more questions, and i'll help where I can.
Of course we also sell alot of different Minie's for the .58. ; )

Hope this helps.
Jeff @ Forefather's Casting

[tangodown]

Well, I am overwhelmed by the number and overall quality of the responses!!! THANK YOU!!

Down to business...
I concur - my lead must be well and truly recycled :)
I need to get a thermometer - the 1 - 9 scale on lead pot heater control just isn't up to snuff
I might need to get a better/tighter and more consistent grip on the mold handles

Will try again in a few days and report back!

[405]

Sounds good. When trouble shooting various casting problems it is always something of a guessing game. One thing about unknown alloys is that they sometimes behave in odd ways. Usually alloys with tin and antimony will cast up slightly larger than pure lead. But, the variable measurements you're getting may also indicate something else is going on like variable temperature, mold halves with something keeping them from mating up perfectly (alignment pins/holes not fully engaging or debris on the mating surfaces) or, as you mentioned, variable handle tension. Try the remedies suggested and for sure report back. We all learn that way and usually these things can be solved with patience and combined effort. Good luck!