Pock-marked boolits

[guninhand]

Hi folks,

I started an alloy with a bunch of dirty looking soft lead (cable sheathing) and have been adding tin and linotype and testing to slowly increase final boolit diameter for a perfect fit. Trouble is all the boolits come out pock marked like a bad case of acne.

I've fluxed this alloy using Antimonyman's pink stuff, marvelux, and wax, and still the pock marks. They are usually distrubuted fairly evenly and as a result the boolits have printed pretty good. But their weight variation is up to 5 grains( it's a 515 grain boolit) and if I could get the pock marks gone I think I'd have real match winners.

If I took a picture the pockmarks would just show up as specks, you'd need a macro lens to show them properly.

The problem can't be the mold cause it cast perfect with another alloy.

Do I just keep fluxing and hope for the best?

Guninhand

[docone31]

I found, a little tin makes smooth.
Definately keep on fluxing. It could be oxides still within the melt. Especially near the spout if you have one. Crud seems to stick to the bottom, and sides of a pot. Stir low, and flux. Then let it sit for a bit, stir again, flux, and cast away.

[hyoder]

Sounds a lot like zinc.
Obviously some sort of impurity or incomplete melt.
What's the temperature of your melt?
What's your source of tin?
Were there any galvanizewd fittings left on the cable sheathing?

[runfiverun]

that weight variation is only 1%
and i would bet the marks are oxides in the lead.

[leftiye]

Ditto on oxides. Are you using a bottom pour casting pot (I'd bet!)? Stir with a stick! Maybe pour all of the metal out and clean the pot. Maybe remelt the lead in another pot (over a Coleman stove?), flux, then pour the lead back into your furnace. Flux it with stearic acid (that's how I got rid of it after 20 years of bs). Ivory soap is a form of stearic acid (pretty much). Cover your lead in the casting pot with crushed charcoal (if it is a bottom pour). This will keep your lead clean and keep oxygen away from the surface of the molten metal (keep more crud from forming).

[Bret4207]

Clean the mould more and turn up the heat.

[Shiloh]

Do they weigh close to the same? Do they shoot okay? Is this just a cosmetic issue. I found that blemishes have little affect on accuracy, other than deformed bases.

Shiloh

[anachronism]

I've had issues in the past where tiny air bubbles looked like black specks in the bullet. I'm with Brett, turn up the heat & make sure the moulds really clean. I went so far as to melt the bullet in a clean ladle with a propane torch to see what was in it. Nothing!. This also ended my experimentation with bottom pour pots. now I exclusively ladle cast, and haven't seen such problems in ages.

[montana_charlie]

I've fluxed this alloy using Antimonyman's pink stuff, marvelux, and wax, and still the pock marks.
Are you using all three 'fluxes' at the same time?
I'm not familiar with the 'pink stuff', but the wax and Marvelux do different jobs...and may not be compatible with each other.
CM

[bigborefan]

I had the exact problem for years and have tried everything possible to remedy this with no satisfaction. I was using a bottom pour furnace and after going to ladle pour, I have never went back to bottom pour. Ladle poured bullets come out perfect while the bottom pour looked like sh@#%t . I fluxed my lead repeatedly before one session and made no differance at all. I used everything possible for flux with but no luck. I changed distance of mould to pour spout, temperatures of mould and lead, cleaned mould in boiling water, tried leaving a cover of charcoal bits on lead surface. Nothing worked. I've cast with WWs, lead-tin for blackpowder loads and even straight linotype bullets with the same results. As someone said on an earlier post on the same topic, it is the charactor of the beast. Go to ladle pour and never look back.

[runfiverun]

it is probably that big boolit thing again, they do like to be ladled,
just as some of mine like the bottom pour and do much better that way.
they can be finicky at times.
i have some that won't ladle some that want to be dribbled into etc....
but the ladle is a good try.

[Bret4207]

I didn't want to fan the flames of the BP vs. ladle issue but yeah, try a ladle.

[Larry Gibson]

Might be enough to open the adjustment up on the bottom pour furnace to allow the melt to get into the mould faster. Most quality furnaces have an adjustment. With harder alloys I cast 500 gr bullets just fine with my Mag-20. Was just a matter of opening the adjustment up. I do ladle pour my lead/tin alloys for BP loads.

Larry Gibson

[guninhand]

What a lot of great advice. I'll clear the decks and switch to ladle pour. I've even got a rowell ladel I haven't used yet.

I've been using a Lee 20lb. bottom pour at 850F. I don't know if Antimonyman is still around but besides being a gentleman he's an expert metalurgist and his pink flux material is based on science.