Another mould/casting problem

[Bub524]

I know this has been beat to death, but here it is:
I have been casting bullets successfully for 30+ years and I have never reached the level of EXTREME FRUSTRATION that I have with casting minies.
I have the following:
-a Gardner mould from Greg Edington that gives me 90% good bullets
-a Lyman 577611 thats results in 98% voids at the apex of the base plug for a 2% yield
-a Lyman 575213OS that gives me 80% good bullets
-a Lyman 578675 that gives me 40% good bullets, most have a hole in the side of the skirt or the skirt doesn't fill out
-Lee trash can mold that puts out 99% good bullets
-Lee Old Style Minie that is 50 %

I use pure lead, the lead temp is between 850 and 950
I have tried a bottom pour Lee and the dipper method. The dipper method gives a higher percentage of good bullets, but I feel anything less than 80% yield is a waste of time. An hour of casting for 12 good bullets is enough to make you want to hang it up.
Round balls are SO much easier.
Did I mention this is EXTREMELY FRUSTRATING??
Any help would be appreciated.

[Southron Sr.]

Put a little pure TIN in your lead pot. A SMALL PERCENTAGE of tin will result in cast bullets that fill out the mould better (hence, less rejects) and produce brighter bullets.

Like I said, just a SMALL AMOUNT OF TIN, too much tin will make the skirts of your Minie's too hard to expand properly.

GOOD LUCK AND HAPPY NEW YEARS!!!!

[Kurt Lacko 7862]

Try canting the mould a few degrees to either side while pouring, obviously as the lead comes up to form the spru you have to level it out. This will give a slight swirl which may/maynot help. It appears your doing everything else correctly.

As a side note, you don't live on the equator do you? Strange things happen there sometimes! Kurt.

[Mike McDaniel]

I think I'l try that mould cant trick myself.

That being said, Minies are a bear to cast. I don't care what you do, the reject rate is going to be pretty high.

[Gary Van Kauwenbergh, 101]

I'm guessing the Edington and Lee molds have aluminum blocks, and the Lyman ones you're having the most problems with are steel. Aluminum blocks warm up to casting temp pretty quick, but will also over-heat if you're casting too quickly.

Steel blocks take longer to warm up than aluminum, but once you get there, you're fine. Either way, you need to get the molds up to the right temp, then find the right rate to cast so the molds don't get too cool or over heat.

Flux well, make sure your spout is clean so you get a good flow into the mold, and leave a healthy sized sprue.

Hang in there. Where are you at in central WI? I'm in Madison, but may be able to connect you with some minie-casters in your area.

[Edwin Flint, 8427]

With the steel moulds, I usually cast the first 15-20 and toss them back in. Takes that long to get the mould up to temp. Then I cast until the pot runs out. No stops. Increases output, decreases rejects. I also cast on the higher end of the temp. scale you mentioned.

Aluminum, same thing except doesn't take as long to get the mould hot. I also preheat the mould on the rim of the pot while the lead is melting. Certain moulds do require the cant.

Stay away from the tin. Pretty bullets, lousy minies.

[tonyb]

While the lead pot heats up heat the steel molds up on a hot plate.

[ken chrestman]

Drill the sprue plate .200-.250 from the back side to allow more volume into the mold. Place mold and dipper horizontal then turn vertical in one motion while holding the dipper in the sprue hole.Let stand a few seconds 3-5.knock open sprue plate and open mold.

I do not add tin.
Heat the mold blocks on a hot plate while the lead furnace gets to molding temp.
Always flux, then cast,I usually get 100 or more before I stop works just fine.

E-mail me and I will mic the exact drill I use if you like, Ken@ShelbySecurity.com

Ken Chrestman, FEC Tennessee

[John Bly]

Casting good minies is largely technique. One must have good lead properly fluxed at the right temp and a good mold at the right temp. Your temps are perhaps a little too high but should work. I use a dipper and pour the bullet over the pot. I get the best results by tilting the mold and pouring the lead down one side of the sprue plate making sure to not block off the air escape by pouring too much, too fast. As the mold fills, bring it to a vertical position while still pouring more lead onto the top plate. On large bullets like minies you must keep a molten column of lead in the sprue while the lead in the mold cools. This will be from 3 to 5 seconds. If you just pour until the mold is full and stop, the sprue hardens and as the bullet cools it will create voids in the bullet because it can't draw more lead into the center of the bullet. These generally show up in the top of the cavity left by the base plug. Voids in round balls are generally not seen, but I would suspect you've got plenty of them in your round balls and never knew it.
I generally enlarge the sprue hole to let more lead in quicker and let the air out. Voids in the skirts are generally caused by the mold or lead not being hot enough or the mold is not vented properly. Voids in the base cavity are almost always the result of poor technique. Keep pouring that lead several seconds after the mold is full and you'll see greatly improved bullets.

[Bub524]

Thanks everybody! I tried the horizontal to vertical pour technique and had 100% return with the 575611 mould!
This was the one I was getting about 2% good bullets from. The 578675 still has skirt problems, or rather I with it.
The other moulds are putting out 95% now.
Thanks again.
Bob