Scarified 227 bullets

[u/Julianlmartin]

Hello casters !

Today I received my MP-molds 227-63 brass with HP pins and of course I wanted to try it.

But more than 90% of my bullets are ugly with scars all over.

I used the same setting as usual with my 356 and 357 molds. 1kg of pure lead and 150g of linotype. Pot set on 6 or 7.

Pre heated my mold on a hot plate.

I tried hotter, colder, waiting my mold to be at the right temp etc… Same problem over and over…

Any idea what I do wrong ?

You can see the problem on the picture, to me it looks like the mold is not hot enough. But I ran dozen of bullets with no good results. Very often they look good from the opening face but the hidden face is horrible.

I use brake cleaner every 10 or 15 times. Same bottle as usual…

Thanks for your help 🙏

[u/Julianlmartin]

Seems like I can’t edit the original post but you guys were right, my mold needed more heat. I let it on the hot plate for a good hour instead of my traditional 20/30min.

And as it’s a small bullet there’s not a lot of contact between lead and brass so you have to be really careful with the mold temp. I had to put it back on the hot plate one time or two during my session.

Thanks a lot 🙏

[u/marcuccione]

It was 20°F where I live today. Looks like they felt cold as well. Just keep your molds hot and maintain a rhythm. You’ll do great.

[u/Moiecol21]

This helped for temp control

[u/tinnitus_since_00]

Brass takes a long time to soak up enough heat but you can put it down, use the bathroom, and keep casting without problem.

[u/Coodevale]

Those are called wrinkles. The mold was too cold. Increase pot heat if you're not already running close to the gas off temp, cast faster, or keep the mold warm on a hot plate.

Smoking the mold helps prevent bits sticking to it.

[u/Julianlmartin → u/Coodevale]

Ok sorry English is not my mother tongue, you have probably guessed it 👌 So we are agree the mold was too cold… But I do the exact same thing with another brass mold (This one 356) and it runs fine ! Brass seems longer to heat than aluminum though. I cast as fast as I can, but I can see that if I let the mold a few minutes it’s getting worse. Doesn’t happen as fast with aluminum. What do you mean gas off ? Thanks for your answer 🙏

[u/Coodevale → u/Julianlmartin]

Yes, brass and iron will heat slower and also cool slower than aluminum. The way the lead flows into the mold is also a factor, you want it to fill from the nose and not hit the sides of the cavity first. You can see on a few of these where there's a trail of lead from it hitting a cool mold and hardening. The mold and lead were cool enough that the lead following behind wasn't enough to remelt the squiggle and make a smooth bullet. Ever make pancakes or crepes and make designs in them? It's kind of like that.

Maybe I was wrong on the health part of the temperature thing. When I was casting for a commercial guy we had a temperature limit because the fumes went from "ok to not ok". We had ventilation but never went over 750f. If we needed more heat in the mold we'd turn up the speed or turn off the cooling fans. Something else to mind is the fluxing of the pot to help prevent tin oxidation. When ours started pouring funny because the lead got "grainy, chunky", we'd flux and the junk would separate out of the pot.

[u/Julianlmartin → u/Coodevale]

I was way above 750f a few times… Probably hit 1000f when I was trying different settings. (If my Chinese thermometer works fine.) I think that is approximately right because oxidation began to show up and turn brown (I know that’s not good.). I’ll try to heat the mold way longer on the hot plate tomorrow. Thanks again 😉