Broken Boolits WTH?

[BulletFactory]

Every now and then, I'll get a bullet that has a crack in it, in the bottom lube groove. Im using WDWW, 75% with 25% of this alloy I got from a gunsmith. It has a BHN of around 16. My pot is at around 750*F.

I stuck a knife edge in the crack, and peeled it open for the photo, it broke apart with verry little effort. The inside is pretty grainy looking. It isnt the first time Ive found these cracks, they are being discovered when I cull the rounds. Im still tossing 1/3 of them back in the pot.

http://i765.photobucket.com/albums/xx294/stainless1911/scan0001-1.jpg

[R.M.]

I've had a few of those lately. Found them when the Star lube blew the rim off.
What I attribute it to is dumping the bullet out of the mold too soon, when the bullet sticks and tips, adding stress to the rim as it leans over just before it drops.

[white eagle]

that is the kind stuff you get when you water drop
from the mold to the water no chance for visual inspection
probably like RM said little to soon

[Rangefinder]

Yup--same thing as dumping ingots out of an ingot mold before they're solidified enough and they end up warped and cracked. In my experience it occurs when the mold is getting really hot and you haven't slowed your pace down enough to even out the temp---AKA, casting in a hurry. ;) Slow your pace just a little, and don't overheat your mold.

[btroj]

What was the alloy you got from the gunsmith?
Looks like a high Sb alloy dropped from a real hot mould. This is what happens in those situations.

Cut you WW about 50-50 with pure PB and this won't happen.

[captain-03]

Yup--same thing as dumping ingots out of an ingot mold before they're solidified enough and they end up warped and cracked. In my experience it occurs when the mold is getting really hot and you haven't slowed your pace down enough to even out the temp---AKA, casting in a hurry. ;) Slow your pace just a little, and don't overheat your mold.

... same experience here!!

[randyrat]

I've seen that with a sticky, hot mold...Fixed it with a little lapping compound.
You are using a hard alloy.

Possible problem is; When you open your mold to drop the boolits, a very small portion of the boolit sticks to the mold and pulls some of it apart. You may also want to let the boolits cool ever so slightly more before dropping into water.

[GabbyM]

I’ve had oven heated bullets crack apart like that. Overheated a batch of 22 caliber bullets and they crystallized when dropped into the water. Many of them were in two pieces. Five hours worth of casting gone in a splash.

[Old Caster]

Whenever you open the sprue and see some lead smear in the holes in the plate you are opening the mold too soon plus, the next pour might not be consistant. You are opening the mold even before that. Another thing to watch is if your sprue shatters in pieces, then the mold has not cooled enough to be opened.

[BulletFactory]

What was the alloy you got from the gunsmith?
Looks like a high Sb alloy dropped from a real hot mould. This is what happens in those situations.

Cut you WW about 50-50 with pure PB and this won't happen.

Mystery alloy, thats why Im cutting it with WW alloy. 75% WW.

I only do 50 pairs at a time, then let the mold cool, while I add lead to the pot, and am waiting for it to warm back up.

[GabbyM]

You need consistency. For most of us that means a clock on the wall.
After you cut the sprue look at the clock and watch five seconds tick off the hand then open and dump into your water bucket. Adjust time as necessary.

I have a six inch fan on the bench to help cool the mold.

As btroj worte more pure lead will help also.

[BulletFactory]

I'll try the clock. I have a 2" fan from a computer or something.

[MT Gianni]

Try air cooled.

[Centaur 1]

I don't feel so stupid after reading this thread. I also use a mystery alloy, it's all range scrap that I blended together. When it's air cooled I can gouge lead with my fingernail, yet when I water quenched them they break apart like yours. I added a few ounces of tin, turned down the heat, slowed down my pace and got a hardness tester.

[geargnasher]

What's happening is a combination of opening the blocks just a little too soon (go ahead and cut the sprue while you're still able to easily do it by hand, when it is just barely firm, but wait about three or four seconds before opening the blocks) and block wobble. As you open the blocks, the bottom (nose end) is spreading apart first, and it literally pries the base off the boolit as you open them.

Check your handles and blocks for excessive looseness or sticking alignment pins. If the blocks don't stay pretty much parallel vertically as you open and close them, shim the handles where they fit into the blocks. That combined with waiting an extra few seconds before opening the blocks will cure your problems.

Gear

[BulletFactory]

Thanks, I have noticed the nose side of the blocks opening up first.

[44man]

Good answers but could it be LAYER CASTING? Lead goes in, sets up and them more lead goes in.
Bottom pour problems?

[canyon-ghost]

I don't use a fan to cool the mold, just leave it open for what I think is about 10-15 seconds. Using cast iron molds though. I leave it open in my hand for a bit, cast again and leave it open. It only takes about 5 times to cool the cavities that much. The trouble is seeing this happen, a guy has to really pay attention to catch it.

[44man]

I don't use a fan to cool the mold, just leave it open for what I think is about 10-15 seconds. Using cast iron molds though. I leave it open in my hand for a bit, cast again and leave it open. It only takes about 5 times to cool the cavities that much. The trouble is seeing this happen, a guy has to really pay attention to catch it.
Why leave the mold open to cool? It might be the reason. I still feel you are layer casting. Keep the mold temp up.

[MikeS]

I only do 50 pairs at a time, then let the mold cool, while I add lead to the pot, and am waiting for it to warm back up.

Why do you let the mould cool while adding lead to the pot? If you don't already have one, get a hot plate, and while waiting for the alloy to get back up to casting temp, leave the mould on the hot plate so it stays at the proper casting temp. On my cheap Walgreens bought hotplate, I have to keep it set all the way on HI to keep the moulds up to temp. You can also use the hotplate to get the mould up to temp when you first start your casting session.

[BulletFactory]

I have a hotplate. What temp is recommended? Im using a 2 cav brass from accurate. (thanks Tom) I also use it to preheat the ingots.

I let the mold cool a bit, but its mostly for the sake of the alloy in the pot, to get that back up to temp.

[MikeS]

I usually heat my moulds to 300 to 350 on the hotplate before casting, and put them back on the hotplate if I'm not casting (like while adding more ingots, and waiting for the pot to come back up to temp) So far I've never preheated ingots, but I'm down in FL, where the ingots are usually around 95deg just by sitting outside.

How does the mould cooling have anything to do with the ingots in the pot?

[grubbylabs]

I will usually cast with two molds so that I can crank out quite a few bullets. I fill a mold then open the spru plate when the lead has solidified enough. then set it aside and fill the next mold and open its sprue plate. then I take the first mold and dump the bullets and refill. This usually lets the mold stay cool enough to cast pretty steady.

[BulletFactory]

If the mold gets too hot, its a good time to add ingots. By the time the alloy warms up, the mold is cool enough to use.

[MikeS]

This is probably the first time (the last 2 posts) that I've heard concern about keeping the moulds COOL enough to use! Usually folks need to get their moulds HOT enough to use!

[quilbilly]

I have had the same thing happen when casting jigs for salmon fishing. I keep my furnace pretty hot in order to get the scale pattern on the fish jigs to fill out. As a result, to prevent the cracking I have to add a little pure lead to soften the alloy. Softening the alloy actually allows the jigs to catch more fish because the anglers can then put on their "secret bend" in the softer lead. I don't water drop the jigs to keep them soft but at the same time I need a harder alloy that will hold paint better. Its a balancing act that has helped me cast better boolits too

[44man]

This is probably the first time (the last 2 posts) that I've heard concern about keeping the moulds COOL enough to use! Usually folks need to get their moulds HOT enough to use!
True. Too hot and quick sprue cutting and dumping can break boolits but usually too cold is the problem.
I heat molds to 500* in a little oven on a hot plate so the first boolits are perfect. Then casting tempo keeps molds just right. Molds should be just below lead temps, not above or far below.
The way those boolits come apart shows a layer that has set before more lead is added. The mold is cold and the flow of lead from the bottom pour sputters.
Boolits way too hot will crumble if dropped too soon. Cutting sprues on molten lead pushes boolits sideways in the mold and deforms them. Speed casting is a waste as bad as cold casting.

[Marlin Junky]

I had a couple 360-220-GB's separate at the grease groove (the weak point) last night. Out of 8-9 pounds of boolits, 2 individual boolits were cracked and one ended up in two pieces. Seemed to be because the mold got too hot. When I slowed down the pour rate, the problem went away. Since I've been using Bullplate lube, I've been casting faster (that's a good thing); however, my boolits are hitting the towel hotter (I can watch a color change as they're laying on the towel). Perhaps your boolit hadn't quite cured long enough before it hit the water and it fractured at that point? Be interesting to find out what would be the result, under the absolute same conditions, if you gently plopped the boolits onto a thick towel instead of shocking them in a pail of cold water. I think the easiest way to rectify your problem is simply back your pot temp off a little. My pot temp last night was just about 750F too and I have a brass 433-315 mold that prefers 700F. There is no one pot temp that works under all conditions... especially with the introduction of excellent mold lubricants such as Bullplate. Bigger molds may take longer to heat to the point where they are casting good boolits (hence, the need for a hot plate) but once they are running properly, 750F alloy may be too hot (depending on your casting rate).

MJ

[BulletFactory]

I'll try air cooling a small batch pretty soon. My gun needs work I cant afford right now, so it wont stop leading, but Id like to see if it gets worse or not.

[1Shirt]

In general I agree with 44 Man. May also be to high percentage of antimony (just a thought) on the brittle side. The only time I have had that problem is when I have not waited long enough to cut sprue. When that happens, it is time to slow down a bit. Casting w/2 molds cures this problem for me. I water drop everything for convenience.
1Shirt!:coffee:

[MBTcustom]

In my opinion, 750 degrees is way too hot. I run my CI molds at 630-650 and my aluminum molds at 675-690. What I do, when running the CI molds, is to keep a designated dish-rag on the table next to the pot. Once I get my rhythm going, I pour the lead, set the mold on the wet dish-rag until the sprue glazes over, open the sprue, drop the boolits, and as I shut the mold and swing it back towards the pot, I notice what the boolits look like. If the boolits are realy shiny, I will skip the rag next time. If the boolits are starting to get a frosty look on the base, I will allow the mold to cool for another half second each time until I start seeing shiny boolits again. When I get it right, I can tune the cooling cycle so that I can cast 50+ boolits (single cavity mold) and they will all be fairly shiny with just the faintest hint of frost on the base, with a shiny dot on the bottom of the boolit where the sprue hole was located. I find it very hard to produce these perfect results with an aluminum mold with out getting frosty boolits but who cares? Helps the 45/45/10 stick better.
If I was to take a flying guess, I would say that you should dump your heat to 700 degrees at the most, and find a way to keep that mold at the right temperature, using the methods listed, or even my method if you want.
Hope this helps, best of luck!

[BulletFactory]

As far as temp, I was following gears advice to another poster in a different thread. Unless I goofed it up somewhere.

He said, heat the pot untill it melts completely, note the temp. Continue until it gets to 100* above that, note the temp. This should help figure the alloy youre using. Then set the temp to 100* above where it melts, and leave it there.

Correct me if I misunderstood.

[geargnasher]

As far as temp, I was following gears advice to another poster in a different thread.

He said, heat the pot untill it melts completely, note the temp. Continue until it gets to 100* above that, note the temp. This should help figure the alloy youre using. Then set the temp to 100* above where it melts, and leave it there.

Bingo.

100 degreesF over full liquidus is a good place to start with most alloys. Linotype and high-tin alloy can be lower than 100-over, pure or near-pure lead will need to be considerably hotter, as much as 200-over with delicate designs. A lot also depends on the individual mould, casting enviroment, and the user's judgement/preference for surface appearance.

Gear

[Lizard333]

I agree that it sounds like you may be casting to quick. I had the same problem a while back. I now cast with two molds at a time, letting one set up while I pour the other. Works for me.

[geargnasher]

I agree that it sounds like you may be casting to quick. I had the same problem a while back. I now cast with two molds at a time, letting one set up while I pour the other. Works for me.

The break is a combination of sloppy handle-mould fit and opening it just a shade too soon. Happens to me a lot with Lee two-cavity moulds if I don't briefly support the bottom of the blocks with a gloved hand to keep the faces parallel while popping the mould open.

Gear

[BulletFactory]

I fixed the mold handles, I left a little bit of slop in them so they would still square themselves, and allow for expansion and contraction. Just added a couple washers that I had filed down to thickness on the pivots, and shimmed the vertical faces of the handles that go against the inside vertical face of the mold cavity in the slot. Luckily I like to weld. :)
ETA. I haven't gotten a chance to cast anything yet. Will report results. ASAP.

[WARD O]

I ran into that once too. I was working with a large mould that made small boolits and was trying to cast very fast to get the mould temp up to achieve better finish and fillout. Boolits would break in half when dropped onto several layers of toweling. Leave the boolit in the mould a few seconds longer.

Ward