Problems w/ out of spec Minie Boolits

[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?

[Moonie]

Alloy and or temp. You are using pure lead?

[mooman76]

I'd say probably temp but it could be alloy also. I was trying out with 50 cal minies a few years ago. The Lee moulds all come at .500. I don't know why they have them such a close tolerence in 50s only, the others are undersized you you can fit them easily in the barrel. Anyway I noticed that some fit tighter in the barrel than others did. I also at the time did not have a measuring device but didn't need one to know they were coming out tight and some tighter. I basically had to drive them in like a maxie so I figured what's the point, might as well use a maxie. I Brought my rifle out to where I was casting to see what I could figure out and I could see that the first boolits were fitting ok but after the mould warmed up they got tighter and with the gun fouled they were even tighter.
Later when I got some calipers I figured out the smallest boolits with a cold mould came out at .501 and they got as large as .504 with a hot mould. You could have a sizer made or cast more and keep the most standard size but I don't think you will see a whole lot of differance shooting, hunting wise anyway. Should be plenty good for minute of deer.

[tonyb]

Are you squeezing the mould with the same pressure. If you relax your grip the bullets will be bigger.

[jhrosier]

My minie mould drops them at about .580 so I had a fellow in a machine shop bore a .575" hole through a piece of scrap steel.
I hand sanded a bit of a taper on one end to lead the minies in square and push them through with a piece of dowel rod in my drill press.
I had the hole bored a bit smaller than I thought I would need so I could open it up if needed.
It shot well enough that I didn't bother.

I dipped the minies in some melted Carnauba Red and let them cool before sizing.
Over about 50 grs of Goex fffg, I fired 40 shots without the need to clean.
I laff my self silly when I watch the fellows with the fancy inlines struggle to reload after even one shot.
Mine drop nearly all the way to the breech with only the weight of the ramrod.

Jack

[Bambeno]

I am with Tonyb on this, sounds like your mould blocks weren't always closed fully.

[44man]

The Minie' should be a tight start in the muzzle and be only pure lead.
I had to lap many of the molds to make a tight fit that way for friends. Do not depend on even base expansion.
We went from not keeping shots on a huge target at 50 to clanging the gong at 200 every shot. Amazing how long it takes one to reach 200!
Just get the mold hot and cast at around 800*.
It sounds like a hard lead is being used where a small difference in temps can have more affect on size. Pure needs a certain temp and will come out more even when that hot.

[swheeler]

Make sure your blocks are closing all the way. Close them and hold them up to a light, if you see light through them look the faces over good for splatters of lead, check the core pin for anything on it holding blocks open. I cast mine from soft lead and run the mold and alloy HOT, preheat the mold on stove burner or hot plate before pouring the first. Was your first bullet filled out completely and wrinkle free, if not your mold may cast at .580 when hot enough to throw a good bullet, pure lead will cast the smallest diameter. If your mold does indeed cast a bullet larger than you need, or want, try spraying the inside of the cavities with mold release or spray graphite, cover the mold faces/vent lines with a piece of paper when you spray.

[tangodown]

I am fairly certain I am using some sort of alloy - at less than a buck a pound I just shrugged and shook his hand.

The spec of the barrel is .577 (Match barrel by Mr Whitacre). So, I am really looking for the .575 per the mold spec. I can most certainly try squeezing the mould (lee) blocks more consistently harder. I can also spray a little mold release too. I had the lead at "8" out of "9" on the temp scale - I don't have a lead thermometer (yet) - but if some one would point me in the direction of an inexpensive one...

Any ideas where I can get pure lead here in the greater Charlotte, NC area?

Thanks for thoughtful remarks

[swheeler]

TD; look at top of Castboolits home page, Rotometals has pure lead and is a lot cheaper than Midway. If you know a roofer have him save you old roof jacks, they are soft and very near pure lead. Smelting/casting thermometers are available through Midway and several others, I think RCBS and Lyman both market one, but in my opinion you don't need one, just turn the pot up wide open, preheat the mold and cast away.