My cast bullets have ugly bases

[Jumbopanda]

For some reason, it's really really hard for me to get a clean cut at the base of the bullet. I have my lead just hot enough to ensure a good fill (6 setting on a Lee pot), but after a few castings, the mold gets REALLY hot, and when that happens, the sprue won't cut cleanly. I've tried letting the bullets cool longer before taking them out, but even after waiting 30 seconds or more, there are still no guarantees. About 60% of my bullets have bumps and voids in the base.

[armyrat1970]

For some reason, it's really really hard for me to get a clean cut at the base of the bullet. I have my lead just hot enough to ensure a good fill (6 setting on a Lee pot), but after a few castings, the mold gets REALLY hot, and when that happens, the sprue won't cut cleanly. I've tried letting the bullets cool longer before taking them out, but even after waiting 30 seconds or more, there are still no guarantees. About 60% of my bullets have bumps and voids in the base.

Humm? What alloy are you casting with? What brand mold are you casting with? I have the Lee 10lb. bottom pour pot and have found that the setting of 6 is very low with wws and with the Lee molds. I run my temps hot with my Lee molds and find that when the mold is really hot I get a better boolit.
You don't need to let your sprue cool very long before cutting. Pour your boolits and look at the sprue. When it changes in color and a slight dimple appears, cut it. This should take only a few seconds. If you let them cool longer it will be harder to cut the sprue. Are you getting any scrape marks on the top of your mold after cutting? If so check the sprue hole for any burrs.

[XWrench3]

if you are using lee molds. i suppose it could happen on any of them though, check the sprue plate hinge screw/bolt. except on lee molds, the nice soft aluminum will get the threads all buggered up way faster from being whacked when they are loose, so it is REALLY important that you check them periodicly to make sure they are tight. i have had a couple of them work themselves loose, and then, yes, you end up with the most important end all fuglied up. i thought about locktiting them, but heat loosens loctite, so i do not think it would do much good. i dont know why they dont make thse things, at least the flat nose molds, nose fill molds. maybe it has to do with getting a good fill out on the big base, trapping air in the bottom??? i dunno?

[randyrat]

Take you sprue plate off. Lay some fine sand paper on a flat suface preferably a steal block. Run the bottom of the sprue plate over the 400 grit paper. Don't get crazy just enough to take any rough edges off.
There may be a burr under the sprue plate hole.

[armyrat1970]

Take you sprue plate off. Lay some fine sand paper on a flat suface preferably a steal block. Run the bottom of the sprue plate over the 400 grit paper. Don't get crazy just enough to take any rough edges off.
There may be a burr under the sprue plate hole.

Good advice but remember after you do that, if you have to, check your sprue hole because the burrs you removed from the bottom of the sprue plate may have left filings, burrs, in the sprue hole that needs to be removed also.

[Bret4207]

Okay, first off this is common. You need your mould hot to get good fill out so you have to work around this. Do as Randy and AR70 say and flatten and de-burr your sprue holes. This is kind of a standard thing you should be doing anyway. Make sure the screw for the screw plate stays where you want it, you may need to add a set screw. For the specific problem of torn bases the best thing I have found is to use the "BruceB" method. Simply touch the sprue to a damp rag. This cools the outside part of the sprue while the inner part is still warm, if you follow me, and usually results in a nice smooth base. Speeds your time up too. It only takes a second to cool the sprue. Play with it a little and you'll find what works for you. This allows you to run a nice hot mould that gives you good fillout and gives you flat base.

If your mould is getting so hot it's taking an unacceptable time for the boolit to cool enough to safely drop you can touch the mould itself to heat sink of some sort like a block of steel or aluminum or run a small fan nearby that you can place the mould in front of for a few seconds. People report that works good. Personally I like my boolits slightly frosty as I always get good fillout that way without having to add tin.

[Wayne Smith]

If you have them try running two molds, alternating. One cools while you fill the other, then cut the sprue of the first, dump, and refill. This allows the mold time to cool, often needed with aluminum molds. I've found with my Mihec brass mold the same thing tends to happen.

[armyrat1970]

If you have them try running two molds, alternating. One cools while you fill the other, then cut the sprue of the first, dump, and refill. This allows the mold time to cool, often needed with aluminum molds. I've found with my Mihec brass mold the same thing tends to happen.

Wayne while I understand what you are saying I have to disagree. If you pour into an aluminum mold and set it aside, then pour into another aluminum mold and then set it aside, then cut your sprue from the first mold you are waiting way to long. It doesn't take that much time for the sprue to cool before it needs to be cut and you're only making it harder.

[cajun shooter]

Are you running that pot by a dial setting or with a thermometer?Lee pots and molds need heat and don't be afraid to run it 775. You need to also buy some Bullplate lube. It makes casting with an aluminum mold fun.I'll bet what you think is hot is not that much.The dial on a lee pot is not always repeatable.

[Jumping Frog]

This discussion could provide far more help to you if you could post some pictures!

[GP100man]

smoke the bottom of the sprue plate good .

[Jumbopanda]

Are you running that pot by a dial setting or with a thermometer?Lee pots and molds need heat and don't be afraid to run it 775. You need to also buy some Bullplate lube. It makes casting with an aluminum mold fun.I'll bet what you think is hot is not that much.The dial on a lee pot is not always repeatable.

Well, I consider it "hot" when the bullets take forever and a day to harden. :p


I have found that adding a little extra mold release spray to the bottom of the sprue plate does help (thanks GP100man). And after a few dozen castings, I dab the sprue plate with a damp paper towel to cool it down just a little. I'm not getting any wrinkles my bullets, so I'm pretty sure the lead is hot enough.

I've managed to reduce my rejection rate down to about 10-15%, which still isn't very good, but at least I'm not tossing half of my bullets back into the pot anymore. For some of the bullets with voids, I just put the sprue plate back on, and put a drop of lead on to fill in the void. These are going to be gas checked anyway, so I'm not worried about the "repaired" section coming off or anything.

After a long day's work, I only manged to crank out a mere 331 good-looking bullets for my .454 Casull. I'm hoping I'll be able to do better in the future.

[crabo]

Read this

http://www.castboolits.gunloads.com/showthread.php?t=57105

[armyrat1970]

[QUOTE=Jumbopanda;668537]
I've managed to reduce my rejection rate down to about 10-15%, which still isn't very good, but at least I'm not tossing half of my bullets back into the pot anymore. For some of the bullets with voids, I just put the sprue plate back on, and put a drop of lead on to fill in the void. These are going to be gas checked anyway, so I'm not worried about the "repaired" section coming off or anything.

This I do not understand

[Bret4207]

If you're GCing and just have a small rip the size of a pencil lead or so and near centered then GC them and don;t worry about it. They'll fly nearly as true as a visually perfect boolit, but you'll get more flyers. If the rip or hole is large or out on an edge then melt it.

[mooman76]

I put bull plate lube on the sprue, that helps plus the other sdvice here. Picures are needed for more help.

[targetshootr]

Try pouring more lead on top of the sprue. I had a mold doing that the other night and that fixed it.

[mdi]

I wouldn't worry about how "hard" it is to cut the sprue. You don't need a six pound sledge or any thing like that, it's just lead! Since you have a six-banger it sounds like you're in a hurry (and "it takes forever and a day") just get another mold and/or slow down. Pour a larger sprue puddle and wait longer...

[fredj338]

Are you pouring w/ the spout in contact w/ the sprue plate? I find this give best base fill out in any mold size. Pour in contact util full then lift away & form a good size sprue. This works w/ steel or alum. molds, single to 6cav 25-1, ww or lino.

[Jumbopanda]

Read this

http://www.castboolits.gunloads.com/showthread.php?t=57105

Wow, that actually helps a lot. I'm getting much nicer looking bases now. Thanks!

[shotman]

Well try the Kroil you will like it . [IF you are young.] you cant fix stupid if your old