lead temp for larger boolits

[hornetguy]

I've done some casting of boolits for the 45 colt, 250 gr or so... and other various boolits down to the 22 Lyman and Bator.
I just tried my new (to me) Lee hollow base mold for the 45-70 and couldn't get the bands to fill out well. I was using pretty much straight ww metal, at 700 degrees, using a thermometer.
If I cast fairly quickly, cutting the sprue just after hardening, the first few were shiny, but had rounded bands. After the first few, the nose started frosting up, and the bands started to fill out, and the base was still shiny, but filled out pretty well.
So, after I check the vent grooves under a microscope to make sure they are all clear, do I.... cast fast, at a lower temp? or slower at a higher temp? I was using a bottom pour furnace, and thought about using a ladle, but haven't tried that yet.
Anybody have the magic combination?

[John Boy]

Anybody have the magic combination?
Hornet - might want to try a mix of 0.5 or 1% Sn with the WW's. Your melt temperature sounds good for the Lee mold

[leftiye]

Hornet, What you describe doesn't sound too bad - if the base and bands fill out, and the nose isn't too frosted. Kinda sounds sorta backwards to me somehow. I usually have higher heat symptoms toward the top of my molds. Kinda sounds like the top of your mold is cooling off for some reason - more than the bottom. Maybe set the mold on a metal plate for a second or two to cool the bottom of the mold off, and then run the metal some hotter. Or use a mold heater to keep the whole mold hot.

[dromia]

Yes, add a touch more tin.

I use a dipper for this mould, get good results, not so with bottom pour.

If the above doesn't work run the melt hot, frosting isn't a problem to me so long as its even across the bullet.

[hornetguy]

Hornet, What you describe doesn't sound too bad - if the base and bands fill out, and the nose isn't too frosted. Kinda sounds sorta backwards to me somehow. I usually have higher heat symptoms toward the top of my molds. Kinda sounds like the top of your mold is cooling off for some reason - more than the bottom. Maybe set the mold on a metal plate for a second or two to cool the bottom of the mold off, and then run the metal some hotter. Or use a mold heater to keep the whole mold hot.


No, you are right.... the nose IS the top of the boolit. Being a hollow base, it is a nose pour mold. Your observations match what is happening.

I don't mind an evenly frosted boolit, as long as it's filled out properly. I will add some tin to the mix and try it again, probably try both bottom pour, and dipper.

Is it pretty much accepted to cover the melt with kitty litter to keep air away? Sometimes I do, last night I didn't .

[44man]

I go against everyone that bottom pours and they will jump on me! :mrgreen:
Use the ladle and hold it tight to the top of the mold until you see the lead go down out of the dipper the second time. First it will just pour in, stop for a moment, then go down again. As the big boolit starts to cool it will pull what it needs from the molten lead in the ladle.
I would also turn the heat up a little.
If you are getting a big divot in the sprue when the lead cools, you are trying to pull lead from an already hardening sprue. Give the boolit lead from the ladle instead.

[13Echo]

I cast this bullet for my Trapdoor out of 30:1 lead tin alloy. I run the pot about 800 F and use a ladle and the mould fills out nice and sharp with few rejects. I agree with the other posters that a bit more tin may be in order and you might try a softer alloy and I definately believe this mould does better with ladle pour and I do have better success at the higher temp. I also preheat the mould in little sheet metal box over a hot plate to about 450 F. Often the first bullet cast is a keeper.

Jerry Liles

[Wayne Smith]

In addition the Lee HB molds have that big base pin that acts as a heat sink, cooling the base of the bullet more quickly. As the mold heats up the opposite will happen as the steel pin retains heat and the blocks cool faster.

[kawalekm]

For best fill-out I use a combination pressure/drop pour. Hold the sprue of the mold firmly against the bottum spout, then open the valve. Once the mold fills, you'll see little squirts of lead shooting out as pressure builds inside. At that moment, drop the mold down and inch and let lead continue to flow out to form the sprue. I can even manage to do this twice with a two-cavity mold. A generous sprue means enough lead will be still molten to be pulled into the mold as the bullet solidifies.

The other suggestion to add tin is also right on. I'd add a 1lb roll of 50/50 solder to 20lbs of wheelweights. That will give you about 2.5% tin in your alloy. That is sufficient for good pouring.
Michael

[44man]

C'mon guys, I have cast thousands of big boolits from pure lead with perfect fill out. WW's don't need a thing added. I use Pure, 30 to 1, 20 to 1, WW's, and harder mixes and do not see a difference in how the alloy makes boolits. Each needs a different temp and procedure but all work. I feel it is a waste to add tin to WW metal.

[Larry Gibson]

Agree with 44man and 13echo, use the ladle and continue to pour moulten alloy allowing it to run off mould back into pot. I have been some what successwith my Lyman Mag 20 with that mould and several other HB moulds for large bullets. The spout stop must be opened all the way allowing the alloy to come out as fast as possible. Also the pot must be kept more than 1/2 full for pressure. Again a very generous sprue is also needed. The ladle works best though.

Larry Gibson

[hornetguy]

I'll try it with the ladle tomorrow night. I have to finish making sure all the vent lines are clear.
If the ladle doesn't make me an expert, I'll try adding some tin.

This is FUN. I'll probably get it figured out about the time the RD group buy molds arrive...

[mroliver77]

I am excited to see so many proposing ladle casting. I was beginning to think that I was the only one here to still use a ladle. I do like my bottom pour but some molds respond better to the ladle. I see many newcomers to casting ask how to get started on the cheap. Seems they are always told to get a 20# bottom pour pot, sizers etc. A cheapo sauce pan, a ladle,a tl mold and some alox should get a fellow going for very cheap. Anyhow I digress. Give that ladle a try and mebbe preheat that mold some. Jay

[lovedogs]

Guess I'm different, I use a 20# bottom pour for all my casting and have excellent results. I use 20:1 and #2 alloys. The big bullets, 500 gr. .45-70's I run about 750 degrees. Hold the mould tight against the spout until it's full then drop down a little to let sprue form on top. Once the mould is hot enough it will work well. I run hot until bullets are slightly frosted then turn down little at a time until they are shiny. Not that frosty is bad but I get my best bullets just below the frosty stage. Edges are so sharp you could almost cut your finger on them.

[HORNET]

hornetguy (why does that sound kinda familiar?[smilie=1:),
I've got to agree with bumping the temperature up . Try 750-775 degrees. That plug for the hollow-base needs to be kept hot to allow things to fill out well. I have been known to use a plant misting spray bottle and give the blocks (but NOT the base) a spritz between pours to keep them from overheating ( you can also touch them to a damp rag or something). You might be able to get good quality using the techniques suggested above for the bottom pour, but I've had my best results using the dipper. Additional tin should not be needed. Play with the timing and adjust the timing as needed. Good luck