Getting large molds to properly fill out. Tips?

[Hanzy4200]

Having a bit of trouble getting proper fill out on a 500 gr Accurate mold for my .500 Linebaugh. I know the issue is not the mold, as Accurate molds are superb. I have run it hot, and bumped tin content way up. No improvement. Bullets are shootable, but not what they should be. Lots of wrinkle around/between lube grooves. Mold way sprayed out with brake cleaner, had some wrinkles, then cooled and scrubbed with Dawn and a toothbrush. Still no change. I have never used a mold over 240 gr, so maybe I'm missing something. On another note, boy does this thing overheat fast!

[Winger Ed.]

Raise the heat. In the alloy and the mold itself both.
If you're casting something soft, add a little bump of tin the thin it out and improve the flow/fill out..

To speed things along, (with a old bottom pour RCBS) I start out too hot.
When I get solid frosting or 'fins', then I start easing back on the heat until they come out with just a small, little bit of frosting.

[cwlongshot]

Yup. Heat. Ya need more and blast it out with brake cleaner too.

[JonB_in_Glencoe]

Cast faster, mold needs more heat.

[lar45]

You might try smoking the cavities lightly.
When I pour big bullets, I like the mold and lead to be Hot, I also like to pour faster and put a big puddle on the sprue to get nice sharp corners.
If you're getting small wrinkles on the sides of the bullets, it could be that the lead is going in too slowly and it's starting to setup?
I've cast 700 gn 500 S&W bullets with this method without any trouble.
Once the mold gets up to temp, you might have to leave the bullets in the cavities for a few more seconds. I've had them bend from dropping too hot into a bucket of water.

[TNsailorman]

Someone on this site gave me a suggestion to try many years ago on the .43 Spanish Lyman die that I was having trouble getting the base to completely fill out. "Try drilling out the filler hole 1/16th size larger than it is now". I was frustrated as the devil so I decided to try it. I haven't had any problems since with that mold. I had already tried a higher temp on the lead and it did help but did not completely solve the problem. Worked for me, your mileage might vary. james

[Mk42gunner]

Ladle or bottom pour? I have had better luck filling large cavities with my bone stock RCBS lead ladle than I have with a bottom pour furnace.

Robert

[DonHowe]

Having a bit of trouble getting proper fill out on a 500 gr Accurate mold for my .500 Linebaugh. I know the issue is not the mold, as Accurate molds are superb. I have run it hot, and bumped tin content way up. No improvement. Bullets are shootable, but not what they should be. Lots of wrinkle around/between lube grooves. Mold way sprayed out with brake cleaner, had some wrinkles, then cooled and scrubbed with Dawn and a toothbrush. Still no change. I have never used a mold over 240 gr, so maybe I'm missing something. On another note, boy does this thing overheat fast!

You do not say how you are pouring, bottom pour, etc. When I shot .45-70 in BPCR Silhouette either 500 and 530 gr bullets I preferred ladle casting. The molds were custom iron single cavity. I had better results after enlarging the pour hole in the ladle I also pressure cast by holding the mold sideways, bringing the ladle to the sprue hole them rotating both vertically together. Alloy was 30-1 ant temp at 750°F +/- and mold temp controlled by cadence.
My partner/spotter got equal or better results with a bottom pour pot but I have not had a pot that I could control the speed of filling the mold as easily as with the drilled-out ladle.

[samari46]

Get one of the small electric hot plates and a piece of steel to cover the heating element. You'll find that when your mold is up to slightly less than casting temp the mold will respond better. And I have used the old trick of opening the sprue plate holes and casting ladle to work as well. Only do one thing at a time to lessen the variables. Frank

[guy_with_boolits]

as others have said, HEAT

but its all guessing until you can measure it..get a SMALL thermocouple or other temperature probe that will let you measure both the lead temperature and the mold temperature so you know whats what

[earlmck]

1) Wrinkles -- everybody else on castboolits can swoosh off their new mold with brake cleaner/wash with hot water 'n dawn and be throwing perfect boolits within 3 shakes. My molds get the same treatment and I still have to cast a couple hundred boolits before they quit giving me wrinkles. Maybe you are related to me instead of all the other casters out there.

2) Base fill-out -- until I have cast a few jillion boolits with the mold I gotta' give it full contact to get good fill-out of the big boolits (I'm a bottom-fill guy). That's after adjusting the flow so it isn't too ridiculous.

[Land Owner]

Aluminum, brass, or iron mold? Alloy? 1, 2, or 3 cavity? Individual spru holes or spru hole trough?

Go to this Sticky, "From Ingot to Target". Download the PDF, or on-line, open to page 67 - Heating the Sprue Plate. Part of your problem lies here.

https://castboolits.gunloads.com/sho...or-Handgunners.

[Four-Sixty]

A trick that worked for me was to warm the mold up to casting temperature, then clean out the cavities with denatured alcohol on a q-tip. I would warm the mold for another couple of minutes then clean the cavities with denatured alcohol and a q-tip again. This solved the problem of persistent wrinkles on a 300+ grain 44 cal mold that was new and prepped with brake cleaner. Before the first and second cleaning I actually saw a slight white residue in the cavities. I suspect this was some component of the brake cleaner that was trapped in the pores. Each cleaning markedly reduce wrinkling. Many here swear by brake cleaner, I won't use it anymore. I suspect that perhaps grain structure, or orientation of the metal's pores just make brake cleaner less than ideal sometimes.

[farmerjim]

Try pressure casting. Several of my molds will not fill out unless I pressure cast them. Also make large puddles of lead on top of the sprue plate to add more heat.

[Cap'n Morgan]

Wrinkles are usually a sign of the mold or lead being too cold. Tiny dimples indicates the cavities are "contaminated" with stuff (often oil) which gasses off when heated. Partly filled grease grooves (rounded edges) can both be a temperature or a venting problem. A partly rounded base is almost every time a sign of trapped air, as this is where the air ends up when the mold is filled.

My pet theory is that venting the top of the mold is the most important part of casting large boolits. The suggestion of enlarging the sprue hole works well, not because the lead fills faster, but because the air has room beside the lead-flow to escape. Once I started cutting venting grooves on top of my molds they behaved much better - especially when pressure casting, where the nozzle blocks the sprue hole during most of the fill.

It's easy to overlook the physics of the invisible air in the mold cavities, but try squeezing bubble wrap, and suddenly the concept of air taking up space becomes tangible.

[GregLaROCHE]

As others have already mentioned, increase the temperature of alloy and make sure mold is hot too. It’s important to have the lead flowing as fast as you can keep up with it. I cast nice 500 grain, 45 cal. boolits in an aluminum mold from Lee. Bottom pour, no hot plate or thermometer. Some molds I find just need time to get broken in.

[Hanzy4200]

It's a aluminum 2 cavity and I am using a bottom pour. The pressure casting is a good idea, I've not tried that. The issue with adding heat is that the mold is already over heating within 4-5 casts at the current settings. At that point bullets are getting extremely frosted.

[GregLaROCHE]

If your Boolits are extremely frosted, the alloy is too hot. Lower the temperature of the alloy and your mold won’t heat up so fast either. Big boolits do heat up a mold faster than small ones. You can cool down a mold while casting by touching the the bottom onto a damp cloth.

[Targa]

As Mr. LaRoche pointed out above, a damp cloth or a sponge. When I cast 400 grain bullets I have my alloy around 800 degrees, every third cast or so the mold gets pressed into that wet sponge to cool it down.

[Larry Gibson]

It's a aluminum 2 cavity and I am using a bottom pour. The pressure casting is a good idea, I've not tried that. The issue with adding heat is that the mold is already over heating within 4-5 casts at the current settings. At that point bullets are getting extremely frosted.

Obviously more heat is not the real answer. The answer is to get the alloy into the mould faster before it cools and starts solidifying. Alloy cools much faster that we thin. As mentioned, using a ladle is probably the real answer. Long ago I discovered the ladle with large bullets [I usually go from the bottom pour to the ladle when the bullet is 325 to 350 gr or more] is the answer as I was casting excellent 400 and 500 gr bullets with the ladle but when I got the bottom pour the bullets came out just as you describe them. Switching back to the ladle and the bullets were excellent again. On the old original Lyman ladle I've even drilled the hole out larger to get the alloy into the cavity quicker. With the new style Lyman and RCBS ladles the hole is large enough. I use the ladle casting technique as described in older Lyman manuals up through CBH #3.

However, After my old Lyman 10 lb furnace gave up the ghost and I got a Mag20 I found with the spout adjustment opened up I can cast excellent 400 gr 45-70 bullets [16-1 alloy]. I keep the alloy temp at 710 - 725 degrees and have the sprue plate not more than 1/2" from the spout when pouring. I also pour so the alloy roils back up out of the cavity forming a goo large sprue , even if alloy runs off the srue plate. I have the ingot mould underneath to catch the run off.