A night of failure…

[justindad]

My casting session tonight had several new items.
1) New alloy - 8lb of 92-6-2, 6lb of SOWW, 6lb of COWW.
2) New casting pot - RCBS Pro Melt 2.
3) I tried casting with two molds.
*
Problem: I could not get good bullet fill-out.
I was getting wrinkles and bad driving bands (particularly between the two lube grooves of a NOE-360-160-WFN), even when I was getting frosty bullets. The spruce plate was hot enough to keep the spruce somewhat liquid for a moment after I closed the pot valve. I stopped using the second mold early, to help the one heat up.
*
I think the answer is add half a pound of tin to the alloy and try again. Getting familiar with the new pot and casting at a faster pace with only one mold will help too.
*
I could be wrong in what I think the answer is, which is why I’m posting this here. I started casting with the lead at 750F and increased it to 810F trying to get better fill-out. After 2 hours I drained the pot and there was quite a bit of lead colored slush/oxides stuck to the walls of the pot. I pushed them into the remaining lead but they did not melt (no surprise), so I scooped them out and fluxed them in my Lee dipper pot. There was a lot of brittle slag from this fluxing. None of my cast bullets have inclusions. I’ve cast with the pure SOWW with no issues. Could the real problem be a significant amount of impurities in my COWW (which was previously fluxed twice)?

[Land Owner]

For starters, please describe the constituents of 92-6-2 alloy.

In the meantime, and until confirmed, from "similar" alloy descriptions:
92 is percent Lead, 6 is percent COWW, and 2 is percent Tin.

If the above is TRUE, then you need to ADD TIN, as the combined alloy is only 0.8 percent Tin. Here is how I derived that:

0.92 * 8 lbs of alloy = 7.36 lbs of Lead
0.06 * 8 lbs of alloy = 0.48 lbs of COWW Lead, and constituents in that (antimony, arsenic, 0.5% tin, etc.)
0.02 * 8 lbs of alloy = 0.16 lbs of Tin

Add ALL of the Lead components together:
7.36 lbs Lead
0.48 lbs COWW Lead (disregard the 0.5% tin = 0.0024 lbs Tin = negligible amount)
6.00 lbs of SOWW (100% Lead^, see reading link below)
6.00 lbs of COWW (incl. whatever else is in it)
19.84 lbs of Lead

19.84 lbs Lead divided by 20 lbs total = 99.2 percent Lead
0.16 lbs Tin divided by 20 lbs = 0.8 percent Tin

Alloys mixed with 2% Tin are 50:1 Lead to Tin. Alloys mixed with 5% Tin are 20:1, and every mixture in between (30:1, 40:1, etc.). Add Tin for better fill out of grooves and edges.

My "Go To" alloy is proportioned 49/49/2 percent - Pb/WW/Sn (Lead/COWW/Tin).

If TRUE,
Your alloy is proportioned 66.8/32.4/0.8 percent - Pb/WW/Sn

^Some very good reading here: http://www.lasc.us/CastBulletAlloy.htm

[GhostHawk]

When my wife came home from the second hand store with 6.5 lbs of pewter I was overjoyed.

Most of that was melted down in an old Lee 4 lb dipper pot and poured into muffin tin to make "coins"
Some was poured into my biggest mold at the time. A .430 310 gr designed for the .444marlin. Those are smaller than the "coins" and anytime I am casting and do not get good fill out with a warm mold after 3 attempts one gets added to the pot. Stirred in well, rewarm the mold. Try again.

It has yet to fail me as a system.

Mostly I cast with roughly half clip on Wheel Weights, half soft lead, range scrap, lead pipe, etc. With 1 % of tin added for fill out.

That is my base alloy. If I am casting higher speed rifle boolits I will add more tin. Lower velocity pistol ammo does not appear to need it.

You should not need more than 2 % tin in any alloy.


Go buy some linotype/monotype with tin/antimony in higher levels.
Find yourself some Pewter and be happy. That is what I did and that was the end of my frustrations.

You do need to have a warm mold, melt that is aprox right temp. I still get a few wrinkles from time to time. Happens, don't let it throw ya.

But good fill should be a given.

[Sasquatch-1]

Sounds like your molds not getting hot enough. Also, you may want to confirm a good reading on the PID using a thermometer to make sure it is calibrated correctly.

[Mal Paso]

A hot plate to preheat your molds really helps. The old method is to stick a corner of the mold in the melt until the lead doesn't stick.

Run 1 Aluminum mold at a time, they lose heat faster than Iron molds.

I run my Pro Melt 2 around 700F with about 2 fills per minute and sometimes lower to 690F if the sprues take too long to freeze. Speed of casting is also a factor.

[mehavey]

Something other than "just add more tin" is the problem here.
(I cast pure lead/800° on some of my 45 ACP loads, many of my 45-70, and all of my Minnies & 12ga slugs)

The sludge in the pot gives me pause, but as other have suggested, get a backup lead thermometer to start.

[farmbif]

you might want to try melting all your alloy together in another pot like a cast iron pot and fluxing it good with sawdust and maybe a bit of bees wax. then when you get all the crud out of your alloy mix pour cast it into ingots and use these clean ingots in your bottom pour casting furnace.

[Dusty Bannister]

If you are using COWW and SOWW in equal amounts, then you may be a little short on the tin. If your 92-6-2 is commonly called magnum pistol alloy, then that will improve the tin content a good bit. Perhaps part of the original issue was tandem casting with aluminum molds in cooler weather. I do not see where you did any alloy cleaning in your casting furnace. Some alloy sticking on the sides of a casting pot are not unusual. It is possible that you picked up something unexpected in the SOWW, but I have to wonder why you drain that pot and then put the alloy in a different pot to flux and reduce. You still have some junk in the casting furnace to remove or dilute with good alloy. The more you transfer the alloy back and forth, the more oxide can form.

I would also consider opening the valve setting to allow a fast flow of alloy into the mold. It also will slow down your casting tempo. If your bullets look like a soft serve cone, it is filling too slowly.

[Rich/WIS]

Think there is more here than alloy composition. Running the numbers his alloy is approximately 96-3-1(-), essentially COWW with slightly less than 1% tin. Have cast for years with range lead at 700-725 which is about 98-2 with no tin added at 700-725 degrees and never had fill issues. He doesn't state what bullet he is casting and long rifle bullets can have fill issues, short and fat pistol bullets not so much. Pour speed makes a difference, too fast and alloy doesn't have time to fill the cavity. Not sure if the COWW may have zinc or other contaminants but would expect that he would have sorted before smelting. If the COWW alloy was sourced elsewhere all bets are off.

[Dusty Bannister]

Fast casting flow can trap air in the cavity. That is not mentioned as an issue. The wrinkles are not stated to say they are the length of the bullet or around the bullet somewhat like lube grooves. It is also hard to state how long "a moment" is. Three seconds minimum is a good place to start when showing how long it takes for the sprue to flash over and freeze.

[justindad]

The 92-6-2 alloy is Pb-Sb-Sn, so the 0.8% tin content in the full 20lb batch is correct.
*
The bullets are 160 grain .357 Mag. 0.630” long.
*
I previously casted 124 grain truncated cone 9mm bullets with only SOWW in a five-gang Al mold, and was fine just running everything hot. That mold has a single, semi-circle lube groove, no crimp groove, and bullets eject well which all adds up to a faster casting pace. So the SOWW alloy should be ok. I probably won’t shoot these bullets - I was just experimenting to see how they would mold.
*
I fluxed the COWW alloy myself, and thoroughly sorted out all zinc by cutting every piece with tin-snips. Fluxed it twice with saw dust and beeswax beforehand.
*
The main mold I used last night is a five cavity aluminum mold for 160 grain bullets to load in a .357 Mag. The bullets have two square lube grooves plus a crimp groove, which makes for slow casting. The sharp corners of narrow, square lube grooves and the crimp groove will present mold flow challenges that the 124 grain mold did not have.
*
I previously ran the 160 grain mold with the 92-6-2 lead diluted with SOWW only, for a tin content of 1.5%. I had a ~30% reject rate there, the mold was hotter, but wasn’t getting any meaningful frosting. I had more frosting last night, but worse mold flow… which makes me wonder a bit about the sludge.
*
I adjusted lead flow rate from fast to slow to fast again. That didn’t help much.
*
I have a brass two cavity round ball .45ACP mold that casts well. Maybe I’ll pour this alloy in that mold and see if I still get bad fill-out. If the .45ACP bullets have bad fill-out, then highly likely I have contamination. If the .45ACP bullets mold well, then I need more tin and a mold thermometer for revolver bullets with sharp edges and narrow driving bands… which would motivate me to get a three cavity brass version of this mold from Accurate or Arsenal, but modify the design for a single, round lube groove.

[Dusty Bannister]

Put the drip pan under the nozzle and open the valve. Do you have a solid stream straight down into the pan or does it shoot off to one side. If the flow is not straight, you need to clear the obstruction from the nozzle that is reducing the free flow of the alloy into the mold.

[justindad]

There was straight flow at throughout the night. That RCBS valve can open much wider than the old Lee drip o’matic.
*
That Lee valve getting stopped up with oxides is what typically ended my casting sessions, which is the #2 reason for getting the RCBS pot. The #1 reason being the faster casting pace allowed by higher capacity & temperature control.

[robg]

turn up temp add a bit more tin.i use 2 molds at a time with lee 10lb pot 45-70 aluminium mold and rcbs 357 mag iron mold have not had a problem once molds up to temp.

[popper]

Your alloy should be about 725F. Mould should be 400F or so. I've had trouble with fast pour into 30 cal rifle moulds, mostly the GC shank as venting is reduced as the mould fills. My pistol moulds are Accurate 4x with a lube groove and don't have a problem. I don't use any tin. Alloy is very hard or very soft, no difference.

[truckjohn]

I've been casting for 15+ years and this thread has me confused. Typically, alloy is designated by the alloy composition, not the mixture of various other alloys. So a 90-6-4 is 90% lead, 6% tin, 4% antimony. Lyman #2 is 90% lead, 5% tin, 5% antimony - or 90-5-5.

The trouble becomes when we're talking about what we mix and shoot... So 50%COWW and 50% SOWW is easy to explain how to mix, but not so easy to pin down what you have. We have no idea what this is... Clip on wheel weight lead is generally left over antimonial lead that the battery recyclers sell off because most of their demand is in pure corroding lead. Stick on wheel weight needs to be soft - so it's a lot closer to pure lead. It could be fairly similar to battery terminal lead, but it may not be, as the primary concern is cheap and doesn't break when installing on a car rim.

So you clip on wheel weights could have an alloy with anywhere between 0 to 3% antimony and 0 to 2% tin, probably with a pinch of arsenic and copper impurity. We usually assume 2% tin and 3% antimony.

To make things more difficult, Tin and Antimony are really expensive. Manufacturers are moving from gravity cast to die cast - which requires a lot less tin to flow and fill out nicely. So where they used to run 2-3% tin for good fill, they now use 1-2% tin... And since it's expensive, guess which way they're going to short the alloy.. Right... Less tin...

And it's even worse when we're talking recycled bullet lead. There are at least 40 different bullet lead alloys used by various manufacturers on top of the commercial cast bullet stuff.

So, anyway, I would try to do some calculations to try to pin down what you actually have, where you need to go, and that will tell you how to get there.

So say you have 50/50 wheel weight lead and stick on wheel weights. That's around 1% tin and 1.5% antimony. That's a really soft alloy that won't cast particularly well.

Say you want 40:1 for pistol shooting, and you're going to get your wheel weight mix there with 50/50 solder. 40:1 is 40 lbs lead + 1lb tin - or 2.4% tin.

In 20lbs, your 1% mix has 0.2lbs tin in the mix. 20 lbs of 40:1 has 0.48lbs tin, so you need 0.28lbs more tin . But since your solder is 50% tin - you will need to add 0.56lbs of 50/50 solder in that 20 lbs.

I would start with a quarter pound 50/50 solder in the 20lb pot and see how it casts. Especially with the cost of solder these days. Be prepared to use the whole half pound. Yeah, I know... I scrounge thrift store solder and pewter...

[Winger Ed.]

I run the heat up until they are a little frosted, then turn it down until the frost goes away.
Some molds seem to do best with a little bit of frosting, ya just need to find its sweet spot.
But don't be bashful about cranking up the heat.

That, and having a good strong flow out the nozzle saves me a lot of issues.
'Strong flow' to me is when a hot mold fills in about 1/2 a second.
For .45cal. 405gr, it might be a little longer, but not by much.

Keep a wire or paper clip handy. No matter how much you clean and flux, the valve will still clog after awhile.

[Gtek]

What about setting up to go just like before with confirmed clean mold, lead and pot @ 725-750 and also have a ladle warming on top. Try about twenty or so dipping and pouring along with new run on bottom pour. Sometimes, some days are just GRRRRRRR! If it was easy everybody would be doing it.

[oso]

I'd say dirty alloy and/or dirty mold. You describe dirty alloy. How do you know you don't have internal inclusions in your castings? If your boolits are irregular then your weights will vary enough you couldn't find boolits with voids or inclusions. How did that alloy work with your .45 RB mold?
If your alloy was clean to start was the new pot contaminated?

[farmbif]

There was straight flow at throughout the night. That RCBS valve can open much wider than the old Lee drip o’matic.
*
That Lee valve getting stopped up with oxides is what typically ended my casting sessions, which is the #2 reason for getting the RCBS pot. The #1 reason being the faster casting pace allowed by higher capacity & temperature control.

if your getting stopped up with oxides or other crud in outlet something is real wrong.
ive cast many thousands of bullets with a little lee bottom pour and never have that problem. I think that its because I flux and clean alloy on separate pot and only use real clean ingots in the bottom pour pot. I have had times when I cast ingots and there seemed to be crud in them and I just remelt and flux and strain again.