casting 30 cal rifle boolits HELP

[oley55]

I am still a novice caster but routinely have had good success casting pistol boolits 9MM-44MAG, but I am really struggling with 30 caliber rifle boolits. The mold is a newer Lee 2 cavity, 160gr, round point. Alloy is COWW with 2% pewter/tin. I preheat my molds on a hot plate garage and have tried casting from 700-775 degrees from a PID controlled Lee 4/20 bottom pour.

From the get go I have had the inclusions shown in the PIC. At first I was convinced I had some contamination in the mold and have gone back to zero several times recleaning but still have the problem. I barely lube the pivot with 2 cycle oil and then thoroughly rub the sprue plate, top and faces with a #2 pencil. Although the defects are most often along the seam line, it also appears beside and in-between.

I have tried and had better success pressure casting (mold held tightly up against the spout) but seem to get too many pull-outs when cutting the sprue and have difficulty keeping the sprue cutter hot enough. With the generous vent lines cut into these newer molds I just don't think pressure casting should be necessary.

I have tried fast and slow flow rates, but have little success controlling the faster flow rates. The bullets depicted below were cast at 750F with a slower pour rate that allowed me to create and maintain a nice sprue puddle.

My cull rate has to be at least 50% as I cull the obvious bad ones while casting and those below are those I didn't cull while casting. I have NOT been dumping culls or sprues back into the pot while casting. FYI even my keepers in the jar contain some with minor defects.

I have two thoughts as to the cause:
1. The inclusion is caused by the drip hanging off the bottom of the spout bounces up off the bottom of the mold cavity and lands on the side.??? The defects are never on more than one side/location.
2. Temperature. My sprues harden with 2-3 seconds no matter how fast I try to go or how large the puddle. I rarely get any frosting and never have to let things cool down.
3. a combination of 1 and 2.

[johnsonian09]

I might try adding some antimony to that mix.

In my experience I get marks like yours when I need to reduce the top back into the pot

I've never used a bottom pour pot.

You might like to try a brass mold at some point. I feel like they take longer to warm up then aluminum but once they are up to temp you can really get casting quick without too many issues

Sent from my SM-J337VPP using Tapatalk

[Super Sneaky Steve]

Since you didn't mention it, I have to ask. Did you clean the mould well before using it? Try using an old toothbrush and some gritty soap.

[Winger Ed.]

I'd run the heat up until they frost with a fast fill, then back it off a little.
You'll end up with some splatter and a big sprue, but that's OK.
Toss the cut off sprue back in the pot, and sweep when you're done.

And don't be bashful about fluxing & stirring.

[JM7.7x58]

It’s still new. Aluminum is porous. There’s oil in them thar pores!!!

Give it another scrub with a toothbrush and soap or a mildly abrasive cleaner like “Bartender’s Friend”. Check for machining burs with a Q-Tip. Then heat cycle it, then spray it with brake cleaner, do this three times. Then smoke it once. Then cast fast until you get frosty bullets.

Then slow down and you should have some nice ones dropping.

I do all that prep to every new mold. I get good bullets this way. Other people fight a mold for thee or four casting sessions until it starts to drop good bullets. It’s the series of cleaning and heat cycles that gets the mold clean.

[Rich/WIS]

Are you sure that temp is correct, that seems high. If the sprue hardens in 2-3 seconds something is not right temp wise, should be a longer. Not sure how you are checking temps but an accurate lead thermometer is a must. I haven't used a Lee double cavity molds in years but don't recall having this issue, or the sprue hardening that quickly. IIRC the issue was mold getting too hot. Short fat pistol bullets are pretty forgiving but the long rifle bullets can be challenging.

[Dusty Bannister]

I agree that the mold is cold, and or oily yet from production. Perhaps you could be clear on how you are preheating the mold and for how long on a hot plate. Please do not waste your effort on making perfect sprue puddles when you clearly have not figured out how to quickly fill the cavity of the mold. Make sure your alloy is pouring freely and in a stream and not a dribble. When using the Lee 4/20 you might have trouble seeing where the stream hits the opening in the sprue plate. If you splash off the top edge, that will cool the alloy and slow the fill. Try to pour down the center of the hole. Perhaps setting the hot in an elevated solid position might be helpful.

Make them frosty, until you get rid of the wrinkles (I do not see inclusions, just where the alloy splattered and cooled before the cavity filled). Then slow down the pace and lower the temp setting.

Is the PID probe at least 1/2 inch above the bottom of the pot and at least 1/2 inch from the side of the pot? If it is too close to the crucible, you are getting an error in your reading.

[Mk42gunner]

I agree with Rich/WIS, 700-775 degrees and three seconds doesn't sound right.

Its been a few years since I cast any .30 cal boolits from a Lee mold, but I don't recall doing anything out of the ordinary when I did. I always preheat the mold by dipping it into the melted alloy, when lead doesn't stick anymore, it is ready to cast.

Its not that I am against using a hotplate, I just didn't trust the wiring in my old house to run both a hot plate and my casting pot on the same circuit.

To test if the drip is causing your issues, blip the valve before you put the mold under the spout. It may just clear things up.

Since you are using a 4-20 you might try ladle casting, I probably dipped half the boolits I cast when I was using mine. An RCBS Lead ladle works great.

Robert

[Bloodman14]

Definitely a temp issue; everything is too cold for good fillout.

[oley55]

thanks for the responses. while y’all were responding I was doing another casting session and kept increasing my temps. It seems 800-810 is the right temp for this mold n alloy combination. I am casting nearly cull free and have just the right amount of light frosting.

for temp measuring I run and control via PID with thermocouple mounted against the base/spout and have a lead thermometer dangling in the lead. What I don’t have is a good way to measure and control my hot plate/mold temp. on my Walmart 1,100 watt hot plate I set just below 5. When I had tried pressure casting the absence of a sprue forced me to occasionally return the mold to the hot plate to get the sprue cutter hot enough for base fill out.

Edit; finally done putzing in the reloading area, here are the boolits cast at 800-810.

[45workhorse]

Oley55
When pressure casting, I start moving the mold away from the spout, then shut the flow of lead off. It gives me a good sprue. I may even top the sprue off with more lead. Just so it has enough sprue to draw from as it cools.
Before putting the mold under the spout, I let little bit of lead out then immediately put the mold under and fill like above. Learned these techniques from a rather lengthy good post on here. I can't remember the poster's name. I have slept once or twice since reading it. Maybe someone on here remembers the article, that I am talking about.
Each mold has it's own secrets you the caster has to find out.

[Dusty Bannister]

Would the OP please provide a photo of how the PID probe is mounted against the base/spout? Generally, the probe is intended to be inserted well into the melt to get an accurate reading. Of course this depends upon which type of thermocouple is used.

[CastingFool]

Although all the suggestions are good and valid, my first thought was that perhaps the lead was not clean enough, possibly causing those inclusions.

[JonB_in_Glencoe]

Casting long skinny boolits is probably the most challenging boolits to cast, other than HP or HB.
Please take the following comments with a grain of salt and not as criticism of your technique...because if it's working for you, you may as well continue...but if you run into other problems, I offer the advice below.

While it looks like you got some good results with the 800+ pot temp, I'd never run a pot that hot. The mold needed to be hotter and while the high pot temp setting works for you, you may look into casting at a faster rhythm to get the mold hotter, instead of running your pot so high.

The thing about the Lee 2 cav mold, especially the Lee 2 cav with new style blocks, is that parts of the mold cool faster than other parts. when one part of the mold is cooler that another part, you will get some of the issues, like what is shown in the Photo in the OP. What I do with Lee 2 cav 30 cal molds (I have a few of them). Preheat them on hot plate to slightly hotter than normal operating temp, then cast until I have problems. Then take a break, put the mold back on the hotplate to "equalize".

...with that said, I also have a 4 cav brass MP mold for the 30 SIL (180gr), that casts awesomely, so I rarely take out the Lee 30 cal molds anymore. The brass is slow to cool and seemingly maintains consistent temp throughout the mold during casting.
That's my 2¢

[Burnt Fingers]

The first thing I'd do is lightly smoke the cavities with a butane lighter.

That has worked for me MANY times when working with a new aluminum mold.

[oley55]

Would the OP please provide a photo of how the PID probe is mounted against the base/spout? Generally, the probe is intended to be inserted well into the melt to get an accurate reading. Of course this depends upon which type of thermocouple is used.

here ya go: https://castboolits.gunloads.com/sho...33#post5054533

The kaowool does a good job isolating the washer and thermocouple from outside ambient air. Heat is trapped under the wool and aluminum bottom plate. Lead thermometer vs thermocouple has never varied more than a few degress. Thermometer is about 1.5" from the side and 1/2" off the bottom.

edit added: pics of lead thermometer and PID from just a few minutes ago. The lead thermometer has an adjustment knob/nut on the back and I have/had calibrated it via a pot of rapid boiling water.

[oley55]

Casting long skinny boolits is probably the most challenging boolits to cast, other than HP or HB.
Please take the following comments with a grain of salt and not as criticism of your technique...because if it's working for you, you may as well continue...but if you run into other problems, I offer the advice below.

While it looks like you got some good results with the 800+ pot temp, I'd never run a pot that hot. The mold needed to be hotter and while the high pot temp setting works for you, you may look into casting at a faster rhythm to get the mold hotter, instead of running your pot so high.

The thing about the Lee 2 cav mold, especially the Lee 2 cav with new style blocks, is that parts of the mold cool faster than other parts. when one part of the mold is cooler that another part, you will get some of the issues, like what is shown in the Photo in the OP. What I do with Lee 2 cav 30 cal molds (I have a few of them). Preheat them on hot plate to slightly hotter than normal operating temp, then cast until I have problems. Then take a break, put the mold back on the hotplate to "equalize".

...with that said, I also have a 4 cav brass MP mold for the 30 SIL (180gr), that casts awesomely, so I rarely take out the Lee 30 cal molds anymore. The brass is slow to cool and seemingly maintains consistent temp throughout the mold during casting.
That's my 2¢

thanks Jon good information.

My original post followed my 5th casting session with that mold and knew I was failing to connect the dots. I had those thoughts about the reduced mass of the new molds and wondered if that reduced mass effected the amount of retained heat energy. Pretty sure I sorta stumbled over the rest while reheating on a hot plate thing but did not follow through as I had pretty much convinced myself I had something else going on.

I guess the moral of the story is follow the the threads...

my first thought was that perhaps the lead was not clean enough, possibly causing those inclusions.

Yes me too and still on my radar.


Thanks again to all for your input and suggestion,
Oley

[gwpercle]

I see the talk about Inclusions ...
I don't see any mention of ... Fluxing the pot ...

I get the alloy melted in the pot , add a little Marvelux ...stir well
Add a teaspoon of wood shavings ... cedar wood from a pencil sharpener ... stir some more
Add a little beeswax to the mix ... stir with little wooden stir stick ...
Keep skimming all the trash that floats up ... still see inclusions ?
Repeat the three step flux .... you have to flux the casting pot to get the inclusions out ...
I use a 20# pot and will flux at the beginning and flux again @ 1/2 way pot level ...
Good fluxing keeps the inclusions out and production goes up ... Trust me on this one !

I honestly think Lee has cut TOO much metal from their blocks ... the last one I bought needs more mass , they cool down too fast in an uneven way ... that just makes it harder for all of us to cast good boolits .

Don't give up the ship , you have to learn and casting boolits is the only way . Looks like you have casting by the tail and on a downhill drag ...
... Keep On Keeping On
Gary

[oley55]

Yea I'm pretty hooked on this casting thing, to the detriment of my range trips/time it seems. I surely do enjoy the ease of do overs with cast boolits and a heck of a lot easier and more fun than pulling boolits, or so me thinks.

[Stopsign32v]

thanks for the responses. while y’all were responding I was doing another casting session and kept increasing my temps. It seems 800-810 is the right temp for this mold n alloy combination. I am casting nearly cull free and have just the right amount of light frosting.

for temp measuring I run and control via PID with thermocouple mounted against the base/spout and have a lead thermometer dangling in the lead. What I don’t have is a good way to measure and control my hot plate/mold temp. on my Walmart 1,100 watt hot plate I set just below 5. When I had tried pressure casting the absence of a sprue forced me to occasionally return the mold to the hot plate to get the sprue cutter hot enough for base fill out.

Edit; finally done putzing in the reloading area, here are the boolits cast at 800-810.

I cast everything HOT!!!!! Haven't run into a situation to where that hasn't produced amazing results. Most times I can't get/keep things hot enough.