head scratcher

[jimb16]

Ok, here it is....I recently bought two new molds. Both are Lees. One is the .30 cal 230 grain for subsonic loads in the 300BLK. The other is a gas check design 155 gr .312 for the Mosin. Both were cleaned exactly the same way, lighter fluid wash with cavity clean out using swabs. A good thorough cleaning done twice to make sure no oils were left. I used my normal prepared boolit metal which I've used for 10s of thousands of boolits. Knowing that the 230 grainer was/has a reputation for casting problems, I cranked up the heat and fluxed the metal carefully. I used exactly the same pot of metal for both boolits. One mold cast near perfect boolits right from the start. The other mold gave me 50% garbage for the first 200 rounds. The question is why? But here is the head scratcher, it was the everyday 155 that was the problem, not the 230 grain subsonic! Everything was identical except the mold. I preped the molds exactly the same way. I checked for burrs using the swabs and removed them. I smoked the molds as is my usual practice using the same candle on both. I pre-heated both molds using the dip in lead method to bring them up to temp. So why did one mold give me problems and the other didn't? Was I holding my tongue wrong? Or were the mold Gods frowning? Darned if I know....

[243winxb]

Different vent line depth? Could the alloy used in the molds be different?

Photos of rejected boolits would help.

[rsrocket1]

It may be that the bigger boolits soaked more heat into the mold and brought the temperature higher quicker. My 6 cavity TL452-230-TC mold heats up within a couple of pours and the boolits fall out of the mold like rain. My 356-120-TC 6 cavity mold at first felt like it took 20-30 pours before the boolits came out satisfactorily. I now dip the 9mm mold in the alloy for a very very long time and pour big puddles on the sprue plate for the first dozen pours.

Unless you can measure the temperature of the preheated mold, you may not be bringing it up to the temperature you think it is.

[Dusty Bannister]

One is the .30 cal 230 grain for subsonic loads in the 300BLK.
The other is a gas check design 155 gr .312 for the Mosin.
Both were cleaned the same way, lighter fluid wash with cavity clean out using swabs.
(Lighter fluid is a petroleum product and might not be the best choice)

Knowing that the 230 grainer was/has a reputation for casting problems, I cranked up the heat and fluxed the metal carefully. I used exactly the same pot of metal for both boolits. One mold cast near perfect boolits right from the start. The other mold gave me 50% garbage for the first 200 rounds. The everyday 155 that was the problem, not the 230 grain subsonic! Everything was identical except the mold. I preped the molds exactly the same way. I checked for burrs using the swabs and removed them. I smoked the molds as is my usual practice using the same candle on both.
(I avoid the waxy oily candle smoke because it leaves a deposit on the mold surface)

I pre-heated both molds using the dip in lead method to bring them up to temp. So why did one mold give me problems and the other didn't?
(Dip does not actually say anything about actually bringing the mold up to temp. Did the mold get smoking hot, or just hot to the touch after 15 or 20 seconds in the melt? Did the bullets show signs of overheating?)

When one mold holds 230 grains per cavity and the other holds 155 grains per cavity, one would expect to need different mold/alloy temps. If these are 6 cavity molds, that difference is really significant. You are not saying anything about that though. Mold sticking, torn bands, creases on the mold surface? Nothing really describing why the castings are 50% garbage is there. Photos will be a big help and absent that, a bit of detailed description. Frosted bullets, shinny bullets, rounded bands, something to work with is helpful. Dusty

[gwpercle]

Some of the new Lee moulds have machining oils that are imbedded deep into the aluminum pores, a lighter fluid and cotton swab got the surface clean but the heat pulled more oil to the surface.
I found a scrubbing with a toothbrush in a pan of acetone , then a casting session to heat and bring up oil, followed by a second scrubbing and a few hours soaking in acetone did the trick. The new moulds require a lot more cleaning than the older styles . I resorted to soaking the blocks in acetone for a few hours .
After all that cleaning and heating , on the second casting session the boolits were great.
One mould just had more oil embedded is a good guess.
This may not be the whole problem , but a good acetone cleaning the second time wont hurt. Don't over think these things it makes you gray haired and you start talking to yourself .
Gary

[Echo]

Logic says that candle smoke is not a good idea, as it carries wax... but that doesn't explain the difference. I have a problem with my 2-banger 230 gr BO boolit - usually only 1 good one, one marginal... and none of that answers the OP question...

[Tripplebeards]

I set my molds on an open flame for about a couple minutes heating the bottom side and then the same on the top side using the coleman stove so they are soo hot that it takes a couple seconds for the lead to harden from liquid state. Also if your using a ladel to pour make sure its just as hot. I casted yesterday with two molds. Both perfecly filled out boolits on the first pour.

[jimb16]

The alloy was the same from the same pot and the same melt. Nothing added or subtracted. Same pot full of alloy. Bad boolits were surface blemishes, rounded bases, creases and rounded driving bands. Varied from one boolit to the next. Metal mass of the 230 is greater than that of the 155 grain mold, so cast faster to retain more heat. Stopped and recleaned the 155 mold, but it didn't make any difference. Both are 2 cavity molds. 155 finally settled down around the 400 boolit mark. I've always smoked my new molds (all makes)and never had any problem with getting wax on the mold surfaces. You would think that with nearly 50 years of experience in casting I could find the answer, but this one has me stymied. BTW, I use a bottom pour pot (Lyman) and leave a nice puddle of sprue lead. I even vary which cavity gets filled first to keep the heat even in the mold. BTW Gary, I'm already gray haired and talk to myself. I'm 68 so I think that is excusable. *LOL*

[Tripplebeards]

Is the heating element going out in your pot not keeping temp?

[popper]

Break the top edge of the mould for a sprue vent, just take the sharp edge off. Typical problem with Al. moulds is mould gets hot but sprue plate doesn't.

rounded bases, creases and rounded driving bands

Mould not hot enough. Rounded bases are usually venting or sprue plate too cool. If you get spots in the GC groove, venting &/or pour too fast - air gets trapped under the sprue. I smoked a Lee mould once - didn't help.

[Dusty Bannister]

How much time passes before the sprue puddle becomes slush or solid?

[trapper9260]

Sound like the mold is not hot enough to me also.Have you try to just do one mold first and then the other one after.You might like to try that. Do the 230gr one of what you want and then turn up the heat for the other one and see from there.I had one mold did what is going on with you and I just turn up the heat on the pot and that took care of the problem.For what I found is that the smaller the boolit the higher the heat needs to be. I had talk with one guy one time about casting a store sometime ago and he told me about he was haveing a problem with casting 32 cal bullets and I ask him how are they dropping and told me lines and all on them.He did not seen that before and all the other cals he cast no problem. I told him he needs to cast them hot. Turn up the heat on the pot. He said i am not dout you I need to do some reading on it more. I was going by what had happened to me and for what work after for me.

[runfiverun]

you know that part of your question where you said they both are LEE molds.
yep.

[JasonYbarbo]

My last .40 lee mold did the same. Took about 200 rounds and then seemed to clear right up. i figure it was machine oil in the blocks.

[w5pv]

Try cleaning the molds with Kroil ,I use Kroil to clean my molds and never have a proble with them. Good luck

[OS OK]

Get a small can of acetone, a small pan and an old toothbrush. Pour enough acetone in the pan so you can flip the mould over cavity down and soak for 10 minutes...scrub the dickens out of the mould face, top, sprue plate and cavity. Do that several times.
Be very stingy with the lube for the pins and hinge screw on the plate or it will migrate right back into one of the cavities and you'll be back to scrubbing again...
Then heat that mould up around 400*F. on a hot plate. Let it pre-heat as the Pb pot is getting ready...when you get back to casting don't stop to admire your work, cast like a house a fire. When you need a break, set the mould back on the hot plate and look them boolits over real good...
This ain't rocket science here...every one of us can do it...yep, even with a Lee mould!

[jarhead0321usmc]

I used the same method I use with my lowers before I spray them. Acetone bath than bake in the oven. The heat from the oven brings out all the oil the acetone missed. Than one more acetone bath. This generally is all it needs for me. Repeat if necessary.

[Smk SHoe]

I might have missed it, but did anyone mention heat cycling it a couple times. I've had a couple Lee 6 bangers that just didn't want to play nice to start with. After a couple casting sessions ( heat them up till bullets look ok, then set it off to the side to cool) and a lite coat of kroil in the cavities and they are casting great.

[Down South]

I've never smoked a mould in my life and I get good boolits. It may take a bit of adjustment but I get er done.
I'd recommend increasing the temp on the heavier boolit. I'd have to see pictures to tell exactly what the problem is but it is many times temperature.

[Tom W.]

My last Lee mold gave me fits,even after scrubbing it with Dawn, hot water and alcohol. I finally blasted it with RemOil and after three casts the boolits came out just fine.. I can't wait to see what the next mold will do...