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Casting RB issue

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Sunbeam

40 Cal
Joined
Oct 30, 2019
Messages
121
Reaction score
27
Hello ( from the UK )

I am sorry if this has been asked already, but I can not find the answer I need, so if anybody can point me to the information, that would be great. Maybe my issue is not so common, hence why I can't find the answer and we can get to the bottom of the problem here?

My problem is I'm getting patches of imperfections (lets call it frosting?) around the top of my round balls. The sides and bottoms of the balls are perfectly shiny, like a mirror, only the tops have patches of 'frosting'. Also, the cut sprue mark on the ball seems to be solid around the edge, but slightly corse in the middle, like the surface of snapped iron.

I assume (as designed) the balls should be perfectly shiny with a nice solid consistent sprue cut off?


I have been casting my own round balls for about a year now and have cast up maybe 3000 balls of differing sizes from .36-.656, all shoot well, all fit the guns, all group well. So I'm not having accuracy problems, but I'd just like to find out why my castings look great all over, but not the tops. I know the tops don't matter, as we load them with the sprue facing forwards, so only the sides really matter, but I'd just like fix my issue that's not a practical issue, if that makes any sense?

Here are two pics of a typical cast round ball of mine (.457) One pic shows the nice shiny bottom (and sides), the other shows a frosted top and rough sprue.
https://ibb.co/PcvMw63https://ibb.co/KxPC67j
My setup is Lee bottom feed pot and Lee alloy moulds, all bought within the last year.
My lead is range scrap from my UK club, mostly 22LR and air gun pellets.
I have been smoking the moulds now and again, but not much and a tiny spot of beeswax to lube the hinge (not enough to get into the mould).
I am starting to think smoking is a problem and I need to get into the mould and polish them with a Q tip and fine metal polish??

Thanks.


P.S,

I smelt my range scrap down in a big steel pot, skim off all the dross, add pure beeswax, mix in and skim again. Then the lead is ladled into small cake tins to form 500gram ingots. So the ingonts are quite pure. I also add a little beeswax into the melting pot from time to time as I add ingots to keep the level up while casting balls.
 
Range scrap can have antimony in it and other impurities. If they shoot well, I wouldn't sweat the looks. Run the heat up a bit and move on. I cast rb with a Lee 20lb bottom pour but use a Lyman steel mold. I have heat set at "8" and I still occasionally get a similar look but they all shoot the same.
 
Frosting is an indication of the heat of the molten lead being too high as the lead is poured. The mold is a little cooler at the bottom of the mold but the very top is just a little bit warmer. Turn the heat down a little bit on the lead pot. However, as @dave951 says, "If they shoot well, I wouldn't sweat the looks". Although I would turn the temperature down,
 
I agree with the others on the frost doesn't hurt a thing. Pure lead doesn't frost or at least as easy. Yes, it's a sign that you are too hot. You can drive yourself nuts chasing frost some times. Seems more common in bullets rather than RBs but turn heat down a little too much and get imperfections, too high you get frost. I tend to ignore it any more.
 
OK Guys, that seems conclusive, lead is to hot :)

I have the Lee bottom feed pot, it is running well, but as you will know, the temp knob is numbered and does not indicate the actual heat and the pot is not have a reg.

I always start the pot about 3/4" from the top and add one ingot as it drops low enough to add one back to the 3/4" start point. I find doing it this way keeps the lead at a fairly constant temp. I've found that if I let the lead drop to 1/2 or lower, the lead gets hot and the lead surface gets all nasty and crusty. I do add a little wax every so often and skim the top to keep the lead in good condition

So should I just stick to my way of keeping it topped up, but turn the heat down a little.
OR
Buy a heat temp reg?


I have played with turning the heat down in the past and discovered what happens when I get it to low, don't want to do that again, wrinkle balls then moulding stops for a 5 minutes with a little help from the pencil blow torch on the spout 😆

Thank you for your help.
 
If you are pressure casting with the nozzle of the bottom pour in contact with the sprue plate the top of the mold is getting heated hotter by the nozzle.

Try leaving a small space between the sprue plate and the nozzle like 1/2" or so see if that clears the frosting on the top of the ball.

In modern bullets a frost bullet is a happy bullet with full fill and sharp edges. Frosted balls won't hurt anything but the looks of the ball.

For the sprue you are cutting to early let the sprue harden for a second or two after the sprue has changed to the solid look. When pressure casting you have to let some lead build up on the sprue plate as you pull the mold down away before shutting of the stream.

I think if the lead temp is to hot the whole ball will frost and if it was pure lead it would be all colored up in blue, purple and yellows. To know the actual temp you need a thermometer .
 
When I'm casting .69cal round ball from pure lead, I run the pot at about 800f as measured by a thermometer. It's about 8.5 on my pot. Mold is steel Lyman. I get some occasional frosting but they shoot fine so I'm not going to get excited over it, and I shoot them in competition. These ain't plinking bullets.

You mentioned a Lee mold. Aluminum molds cast at a different tempo than a steel or brass one. They heat up fast but also cool fast. Your ambient room temp can affect that tempo. I've seen it when using an aluminum mold here in NC during the winter v what happens in summer. I'd suggest not changing the temp but slowing your tempo a bit.
 
I think your rough sprue cutting will disappear after you turn the heat down because it will cool quicker. I do my pot about the same as yours except I keep mine higher. and soon as I can get a ingot to fit, I put one in. Just turn your pot down a little at a time. Like 1/2 a number. I might add that I ladle pour but it should make that much difference here. I have heard of some with bottom pour pots, putting a small amount of clay kitty litter(not used) on top the lead. It cuts down on oxidation. Don't know if I would do it, but thought I would mention it.
 
I read an article about casting bullets years ago, and the author said to force him to show down he cast with 2 different molds at once.

I tried it, pouring lead into one mold, setting it down, pouring lead into a 2nd mold, setting it down, picking up the 1st mold and cutting the sprue.

I found my bullets have perfect noses, and the molds don't overheat as much.

If you only have 1 mold, simply count to 10 or 15 after filling your mold, then cut the sprue.
 
I have three moulds I could actually use at the same time, so I can move over to that system :)

Kitty litter on the top of the lead is a good idea, although since running the pot fuller, the muck on the top is much less as the lead is cooler. I guess sand would work as well, or anything that can block out the air that does not burn?

I know it means nothing really, but my knob was at 7-1/4. The next time I cast, I'll set it to 6-3/4 and use two moulds. I think that will help.

As I said before, the balls come out OK for shooting and shoot well, it would just be nice to have them uniformly shiny just to look nicer :cool:

Thank you guys, you have helped quite a bit :)
 
Definitely good to rotate through molds as you cast. Looking at your pictures, I really don't see any "frosting" (may be the light in the photo or my old eyes).

I do see where a little chunk(s) has been pulled out at the sprue, which is a sign the metal is still too soft to cut, or there is enough antimony or other hardener in the alloy to promote brittleness.

Those are the two areas i would look at first, and as far as frosting, as others have said I really wouldn't worry about it, it is purely an aesthetic condition.
 
From what I see and my MANY years of casting modern and muzzleloading projectiles your heat is not too hot and that sprue to my eye is not frosted it looks torn
P1010087.JPG
P1010088.JPG
P1020104.JPG
P1010826.JPG
. I agree with Maven that your sprue cutter maybe dull and you are cutting off the sprue too soon. If your lead melt was too hot you would see frosting all over the projectile not just where the sprue cutter sheared off the excess lead. That range lead maybe adding to your issue although I would not think by much if any. I also smelt my scrap lead in a separate "pot" two times before I cast pucks of my bullet lead for my casting pot.
 
I would agree that you need to wait a little longer before popping the sprue plate off. Other than that, they shoot well so who cares?
 
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