Advice on troubleshooting Cast Boolits

[pdgoutdoors]

Hi all,

I’m an experienced reloader, but just started casting about a month ago. I have spent countless hours reading on this forum and the information has been invaluable. I have been able to troubleshoot most of the problems I have come across so far, but there are two Boolit imperfections that I just can’t figure out.

First, on the base of my Boolits where I cut the sprue, sometimes I get a nice smooth bottom and sometimes it sucks into the Boolits a little bit. I have tried changing sprue plate tightness, heat (I finally got temp control down), and pour height. The image below shows what I’m trying to explain. Is that a big deal or is it acceptable?

Second, I am sometimes getting rounded driving bands and crimp grooves. I am getting them from the same cavities that will cast a perfect boolit the pour before and pour after. This particular one is an MP 454640. The mould was cleaned correctly when I got it and heat cycled before use.

Thanks in advance for any knowledge bombs about to be dropped.

[pdgoutdoors]

Attachment 320507

[Dusty Bannister]

That is a shrinkage void. Sometimes resulting from a small sprue puddle, or sprue plate chilling the puddle right at the smallest point of the cone of the sprue hole. Knowing if you are casting in an unheated area, or an excessive draft might be a consideration. Bottom pour pots can lose heat as the stream falls from the nozzle to the sprue plate. Loss of heat during the pour can also result in fill out issues as well. Identifying your alloy and casting temperature are always a good idea.

[jsizemore]

Got any close pics of the mold block top and the upper mold faces? Could be a venting thing. Bullet base doesn't look round but your sprue cut looks good. Looks like the last air isn't making it out as the cavity fills.

You'll find the right alloy temp that fills out but isn't so high that it will start plugging the vent grooves cut into the face of the mold. Rate of pour also affects it. You have to find the balance of alloy temp, mold temp, rate of pour and venting. It isn't like everything has to be an exact amount but there is a band where everything works with minor variations. 2 seconds change from pour to cut can make all the difference in irregular fillout and just right. Experience will teach you as long as your paying attention.

[charlie b]

Since you are also getting some with rounding then I'd say the mold is a bit too cold and/or the pot temp is too low.

[pdgoutdoors]

Got any close pics of the mold block top and the upper mold faces? Could be a venting thing. Bullet base doesn't look round but your sprue cut looks good. Looks like the last air isn't making it out as the cavity fills.

You'll find the right alloy temp that fills out but isn't so high that it will start plugging the vent grooves cut into the face of the mold. Rate of pour also affects it. You have to find the balance of alloy temp, mold temp, rate of pour and venting. It isn't like everything has to be an exact amount but there is a band where everything works with minor variations. 2 seconds change from pour to cut can make all the difference in irregular fillout and just right. Experience will teach you as long as your paying attention.

I’ll snap a pic when I get home for you. Are the way the bases are now a big deal, or will they shoot just fine?


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[MostlyLeverGuns]

Mostly they shoot fine, depends on range and your accuracy requirements. Might start to notice accuracy issues past 100 yards.

[JonB_in_Glencoe]

Premature sprue puddle freezing.
Pour larger sprue puddle or keep sprue plate hotter.
When you are pouring alloy, think of it like pouring Heat.
Also, you want the sprue puddle molten as the boolit freezes ...as the boolit freezes it will shrink a bit, but if there is molten alloy in the sprue puddle, the boolit will pull that alloy into the cavity ...avoiding the shrinkage you are seeing.

[jsizemore]

Run them through the sizer and you can't tell the difference. You start shooting at the 200 yard line you'll need to hold the middle.

[WRideout]

That is a shrinkage void. Sometimes resulting from a small sprue puddle, or sprue plate chilling the puddle right at the smallest point of the cone of the sprue hole. Knowing if you are casting in an unheated area, or an excessive draft might be a consideration. Bottom pour pots can lose heat as the stream falls from the nozzle to the sprue plate. Loss of heat during the pour can also result in fill out issues as well. Identifying your alloy and casting temperature are always a good idea.

I agree. You didn't say how you are casting. It would help to know if you are casting with a spoon out of a dipper pot, or using a bottom pour pot of some description. Also, it would be good to know what your alloy is. A little tin added will often clear up the incomplete fill problems.

Also, which mold you are using. IME, aluminum molds like to run fairly hot, as compared to steel.

I was having a lot of trouble such as you mentioned, however I acquired a Lyman spout type dipper, and that cleared up most of my difficulties.

Wayne

[pdgoutdoors]

I agree. You didn't say how you are casting. It would help to know if you are casting with a spoon out of a dipper pot, or using a bottom pour pot of some description. Also, it would be good to know what your alloy is. A little tin added will often clear up the incomplete fill problems.

Also, which mold you are using. IME, aluminum molds like to run fairly hot, as compared to steel.

I was having a lot of trouble such as you mentioned, however I acquired a Lyman spout type dipper, and that cleared up most of my difficulties.

Wayne

I am using a MP brass mould poured out of a Lee 4-20 bottom pour. I’m just using straight up range scrap right now while I learn. I don’t have any access to tin and I collected about 50lbs of range lead before I started learning.


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[frkelly74]

My philosophy on range lead. " It worked once, it will probably work just fine again." Tin can be had from Pewter which may be found at thrift stores or yard sales, Sometimes also old rolls of solder. You really do not need much tin if you are using reclaimed boolits, there is probably tin in there already. If you render your lead from jacketed bullets you might get some benefit in better fill out with some small amount of tin/pewter/solder added. I think of casting more as an art than a science.

[Winger Ed.]

Welcome aboard.

Good advice above.
Range scrap is usually pretty good if a lot of it comes from a pistol range where folks are shooting
cast boolits. Especially if there is a lot of the harder commercially cast ones in the mix.
The Lead melted out of jackets is usually pure or real close to it.

To avoid rounded edges, I run the heat up until I get just a hint of frosting.
To improve the fill out if that doesn't quite work, I'll add just enough 94/5 solder until it flows better.
Any place that sells Pluming stuff will have it.
The down side is the price has gone up so much, it's higher than giraffe lips now days.

Another thing that may help is get a few ingots of the hard alloys from one of the seller/sponsors here.
For handguns, the alloy can be rather soft, with just enough 'goodies' in it to get a good flow/fill out.

There is a learning curve to casting, and you'll get it figured out pretty soon as to what temps. work,
and you establish a rhythm to your heat, mold fill, & drop timing.

[Shopdog]

Keep notes;

Dosen't need to be a "novel"... just a few lines on temps,alloys,pour rates,etc. Cpl reasons,there can be gaps in your time at the casting bench and,as you get more moulds it's just nice to look back at the notes.

Good luck with your project.

[Minerat]

I started having rounded edges on the base and found if I "break" the top edge of the mold with a small 45° angle on both sides it vents and gives me a flat base. I use a triangular stone for this before I break in the mold. I also found that when using a bottom pour pot that the wider I have it open, the larger the puddle and counting to 5 after it frosts helped stop the cavity in your photo. Also, at the ranges I shoot with my big bore pistols it did not affect my accuracy. On the other hand if the cavity really mattered why are there hollow based boolits or for that matter beveled bases.

For me if the handgun goes bang, that's the fun, I'm not good enough with one to worry about accuracy better than pie plate at 25 yards.

[wv109323]

My .0 2 cents. The sprue plate will cool quicker than the brass mold body. Cast as fast as you can to keep the sprue plate hot. Slow down when you start to get frosted boolits. I preheat the sprue plate as well as the mold on a separate hot plate.
Get the lead into the mold as quick as you can. Hold the mold where the stream of lead goes directly into the sprue plate hole. adjust the mold till there is minimal distance between pot and mold.
Pour a liberal sprue to allow for shrinkage.
Make sure the mold vent lines are open.
Insure your lead is back up to your casting temp. after lead is added to refill the pot. This was one of my pitfalls until I started using a PID. The recovery rime was much more than I realized.
Cast with a full pot of lead. Lead will get into the mold much quicker when the pot is full.
Weigh your best and worst boolits to see how much weight variation there is between the two. Plus or minuses 2 per cent will not hurt accuracy.
Bad boolits will look much better after sizing.
Your sprues look acceptable.

[Bazoo]

That pic is a pulled sprue. It's main cause us from cutting the sprue just a touch too soon. If you wait about 5 seconds longer it won't do that.

Getting the occasional rounded bands/base is likely from allowing the sprue puddle to flow into the adjacent cavity or off the side of the mould cavity. The metal that's flowing away from the cavity you're trying to fill keeps the weight of the molten lead from pushing downward into the cavity to fill out the bullet completely. A larger sprue puddle works better than a small one, in part, because the weight of the molten metal is pushing on the liquid metal in the cavity, causing better fill out. An alloy that this rich in tin has a lower surface tension, and doesn't do this as badly. Fluxing with beeswax also helps lower the surface tension for a short while, until the beeswax is burnt up.

[uscra112]

Premature sprue puddle freezing.
Pour larger sprue puddle or keep sprue plate hotter.
When you are pouring alloy, think of it like pouring Heat.
Also, you want the sprue puddle molten as the boolit freezes ...as the boolit freezes it will shrink a bit, but if there is molten alloy in the sprue puddle, the boolit will pull that alloy into the cavity ...avoiding the shrinkage you are seeing.

This ^^^^^

Charlie Dell taught me to forget the Harry Pope business about holding the spout to the sprue plate until you take it away. Let some molten lead run over the plate to keep it hot. Only way I can get good yield when casting my 60 grain .25 caliber bullets.

Second issue - my guess is that when you get rounded bases and lands you've delayed too long between pours, and the mould cooled off. Aluminum moulds are especially susceptible to this. Keep your rhythm going, and again, keep the sprue plate hot.

[waksupi]

The BruceB method of curing torn bases, is to have a wet sponge to touch the sprue to once it has started to frost. It increases production considerably. I use a can lid with the sponge, and water in the bottom of the lid. Add water as needed.

[rintinglen]

That pic is a pulled sprue. It's main cause us from cutting the sprue just a touch too soon. If you wait about 5 seconds longer it won't do that.

Getting the occasional rounded bands/base is likely from allowing the sprue puddle to flow into the adjacent cavity or off the side of the mould cavity. The metal that's flowing away from the cavity you're trying to fill keeps the weight of the molten lead from pushing downward into the cavity to fill out the bullet completely. A larger sprue puddle works better than a small one, in part, because the weight of the molten metal is pushing on the liquid metal in the cavity, causing better fill out. An alloy that this rich in tin has a lower surface tension, and doesn't do this as badly. Fluxing with beeswax also helps lower the surface tension for a short while, until the beeswax is burnt up.

+1. those pesky divots occur because you are cutting the sprue before it has fully frozen, so some of the granules of lead that are frozen, are ripped out from the ones that aren't quite there yet. Another second or two before cutting and you'll have a nice smooth base--that won't shoot very much, if any, better. A big sprue puddle and 1-2% tin will help prevent rounded corners.