Bullet casting decision tree for troubleshooting

[EDG]

We are all familiar with people asking for help with casting problems. I know I have asked my share of questions. It seems that we could put together a descision tree for solving casting problems similar to the trouble shooting charts found in automotive repair manuals.

For example there would be a list of common problems with a chart of the common solutions taken in order of easy to difficult to correct.

Poor fill out >> mold clean >> correct temperature >> alloy has enough tin >> mold venting adequate>>>mold needs smoking >> etc etc

Bullets stick in the mold>> mold parting line burrs >> mold too hot/cold >> etc etc

Bullets have parting line fins and whiskers>> mold blocks not closing>>metal too hot>>alloy has excess tin

Sometimes there will be one branch that flows into another or two branches may need to be followed at the same time.

This would make a good sticky if the common problems and their solutions could be charted by the graybeards here.

[Cherokee]

Good idea...I like it.

[Artful]

It's been done before...
http://www.gunweek.com/2004/feature1201.html


Solving Some Common Problems Encountered when Casting Bullets by Aaron Bittner

If you know someone who casts bullets, he has probably already bent your ear about how he turns scrap lead into first-quality bullets in his spare time. He probably has shown you some of his work. He might have even given you some bullets out of charity, and you have to admit—they look pretty good, especially for something somebody made in their garage.

So you go out and find a lead pot and some molds, lay in a supply of ingots, and try it. And that’s where you discover what your buddy didn’t tell you: There are plenty of ways you can go wrong casting a bullet. Fortunately, they’re all easy to correct.

http://www.gunweek.com/2004/pix1201arc/2.jpghttp://www.gunweek.com/2004/pix1201arc/1.jpgPoor Mold Fill-Out
One of the most common problems first-time casters have is that the lead doesn’t completely fill the mold cavity. Corners that should be sharp are rounded, and the whole bullet looks like a bar of soap that’s been through half a dozen showers.

There are several causes for poor fill-out, but the first thing to check is temperature, both of the alloy and the mold. If either the alloy or the mold is too cool, you’ll get poor fill-out. Solution? Let the lead heat up some more. With an electric pot don’t try pouring the first bullet until half an hour after you’ve turned it on. Also, pre-heat the mold by dipping a corner of it into your melted alloy for a few seconds. If the alloy “freezes” into a crust around your mold, it’s not hot enough. When alloy and mold are hot enough, you can pull the mold out of the mix clean, or nearly so. Mold manufacturers are squeamish about this for some reason but I have never damaged a mold, either aluminum or iron, by dipping it.

Another reason for poor fill-out is the alloy flow rate. If you’re ladle-casting as many first-timers do, this is a matter of technique. You must pour the lead faster. If you are using a bottom-pour pot, adjust the valve stop screw to allow the alloy valve to open further. The lead should flow in a round, straight stream about 1/16 inch in diameter. Sometimes you will see a bullet that looks good except that the base has not filled out. When that happens, make sure your lead and mold are sufficiently hot, and pour a bigger sprue on the top of the mold (I’m not sure why this helps, exactly, but it does).

http://www.gunweek.com/2004/pix1201arc/3.jpgPoor mold ventilation can also prevent proper fill-out. Bullet molds these days have vent lines scribed into the mating surfaces of the mold blocks. These can get blocked during casting and cause your bullet quality to head south. The fix is to unblock the vent lines, either with a carefully applied wire brush or by a very carefully applied scribe or knife tip drawn through the grooves.

If the bullets still aren’t what you’d like them to be, try force-feeding the mold by putting the sprue plate in contact with the pour spout. Let the pressure of the alloy column push the alloy into the corners of the mold. When this works, your raw casting may have lead “hairs” along the parting line where lead alloy actually flowed into the mold’s vent lines. When this happens you know you’re getting good fill-out.

The third most common reason why bullets don’t fill out the mold is lack of tin (or the presence of zinc) in the alloy. If you’ve played with the temperature and the flow rate and are still getting second-rate bullets, try adding some lead-free solder to the mix. Solder will bring up the proportion of tin in the alloy, which makes it freer-flowing and better able to fill the mold.

Sometimes you will run across a melt that won’t respond to tin; if you’ve eliminated every other possibility and your alloy contains wheel weights, you probably have some zinc in the melt. If right after the alloy becomes liquid you stir it and see what looks like tiny granules moving just below the surface, that’s zinc. You may be able to dip out the zinc granules at this stage (they tend to float), but you’re better off throwing the whole batch away and starting over.

http://www.gunweek.com/2004/pix1201arc/4.jpgWrinkled Bullets
Sometimes you’ll pour a bullet that appears “wrinkled.” There will be visible creases and knit lines on the surface of the bullet, and tiny craters or pits as well. This is a sure sign of oil or grease in the mold cavity. If you oil your iron molds between uses or if you use Lee molds according to their instructions (which call for lubricating the sprue plate with paraffin) you will encounter wrinkled bullets from time to time.

The solution is simple: Wash the mold. This can be done either with mineral spirits or some other solvent, or with a water-based degreaser. Dish detergent works fine. A stiff-bristled brush such as an old toothbrush will help get the cavity clean. Lee mold users will learn to be ver-r-ry careful when they dab a little paraffin on their molds, or they’ll do the wash-and-wax boogie all day long. Make sure the mold is completely dry before you use it again.

Finned Bullets
This is an easy one. If the bullet has “fins” on it, the mold blocks aren’t closing completely. This usually means that you have to wire-brush or scrape lead deposits off the mating surfaces of the mold. Sometimes a worn mold will show “cratering” around the alignment pin holes. This can be amended by lightly honing that mold face flat on a whetstone. (Note: Do this with fear and trembling lest you ruin your mold.)
http://www.gunweek.com/2004/pix1201arc/5.jpgA .44 Keith (Lyman 429421) with a big ol’ fin on the nose. Poor fill-out also indicates that the alloy or mold wasn’t hot enough. If they both had been, the fin would go all around the profile of the bullet. Note the vent lines cast into the fin.

Flanged Bullets
Sometimes you may see a bullet that looks great except for that big ugly flange on the base. This is a sure sign of a poorly-fitting sprue plate or mismatched mold blocks. Look for lead deposits in the space where the flange forms, and scrape or brush them off. Make sure that the sprue plate screw is snug, and that the bottom of the sprue plate and the top of the blocks are flat. You can hone these surfaces on a whetstone as well.

Frosted Bullets
Frosted bullets are really not a problem, but they can be a sign that trouble is coming. “Frosting” happens when the alloy in the mold blocks cools and solidifies so slowly that it allows big, visible crystals to form as it hardens, making the bullet look galvanized.

While frosted bullets work just fine, they are a sign that the mold blocks are on the ragged edge of being too hot. If you start to see frosted bullets, it’s probably a good time to rest the mold for a few minutes, or at least slow down your pouring cycle. If you don’t cool the mold, you will start to see lesions on the bullets and smeared sprues.

Bullet Lesions
What I call “bullet lesions” are the result of incomplete mold fill-out, but of a different sort and for different reasons than I mentioned earlier. What happens is that the alloy and mold are so hot that the alloy superheats air in the mold cavity as it fills, leading to a pressure bubble against the inside of the mold cavity. This bubble keeps alloy from contacting the mold surface, resulting in a crater-shaped lesion at that spot. These frequently show up on the bullet base, and sometimes in the driving bands. This problem can be addressed by cooling the mold or (to a degree) by pouring the alloy more slowly into the mold.

Smeared Sprues
http://www.gunweek.com/2004/pix1201arc/6.jpgIf the base of the bullet smears or the sprue does not cut cleanly when you open the sprue plate, you’re opening the mold too soon, and very likely running the mold too hot. A smear happens when there are spots in the bullet that are still melted when you open the plate. A rough sprue happens when you open the mold before it completely solidifies. The solution? Let the mold cool more after you pour it, or quench the sprue on a damp towel before you open the mold.

Blems
With bottom-pour pots you will sometimes see little dirty spots on the surface of the bullet. These can be frustrating, especially after you’ve fixed all the other problems. Don’t load these bullets. The dirty spots are little chunks of grit (tin oxide and other junk) that get in the alloy, and they don’t belong in a gun bore. Such spots are a signal for you to clean your lead pot. Scraping and fluxing can get you by for a while, but sooner or later you’ll have to empty the pot and scrub the trash out of it. Ladle casters don’t usually have this problem because they dip their alloy out of the middle of the pot, where the alloy is clean.

http://www.gunweek.com/2004/pix1201arc/8.jpghttp://www.gunweek.com/2004/pix1201arc/7.jpgProperly, once you get in the groove, so to speak, you’ll find that you can recognize problems and correct them on the fly. This will enable you to cast a mortal lot of bullets. And that’s a good thing, right?

Your shooting buddies will think so, especially when you give them some bullets you made in your garage.

[RedHawk357Mag]

Excellent info. Great idea. Thanks to you both.

[EDG]

What causes bullets to be frosted like they are too hot yet still be wrinkled on the nose like it is too cold?

[Garyshome]

Thanks for the post.

[MGnoob]

What causes bullets to be frosted like they are too hot yet still be wrinkled on the nose like it is too cold?

I've never answered anyone question before, or tried to would be more accurate.When i noticed that, i believe it was too cold of a mold and to hot/fast lead pour. it could have been oil in the nose of the mold, mine where new when this happened, i did clean them but maybe i didn't do a good enough job.

When i first started, i used a guide like Artful posted and some books i had..sometimes a picture worth a thousand words.
When i ran into a problem, i managed to come here and get an answer without having to ask the question, but i am sure some things are not covered or difficult to find.

[462]

What causes bullets to be frosted like they are too hot yet still be wrinkled on the nose like it is too cold?

One possibility is an overly hot mould that still has residual manufacturing oils within its pores.

[MGnoob]

One possibility is an overly hot mould that still has residual manufacturing oils within its pores.

This makes sense.. when I was having trouble the first run. i had more then one thing wrong,, that's why "decision tree" are great but sometimes you have to look at all the "branches".