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8683jb
10-11-2012, 03:18 PM
I recently bought a Lyman #575213-OS Minie bullet mould and am having a tough time getting pure-lead bullets to cast without a having cavity near the top of the hollow base. I've tried faster/slower pouring rate, tipping the mould, hotter/colder temp., still with about a 90% reject rate! What am I doing wrong? Thanks for the help!

44man
10-11-2012, 03:35 PM
I recently bought a Lyman #575213-OS Minie bullet mould and am having a tough time getting pure-lead bullets to cast without a having cavity near the top of the hollow base. I've tried faster/slower pouring rate, tipping the mould, hotter/colder temp., still with about a 90% reject rate! What am I doing wrong? Thanks for the help!
:bigsmyl2: HEE HEE, yes! As good as I cast, some hollow base molds drive me up the wall. I have used molds that were casting perfect and then the next would have that cavity. I tried everything with vent lines, heat, etc. It is disgusting to say the least.
I am sorry but I can not answer, it happens to me. Those molds have bad spirits! [smilie=l:

milkman
10-11-2012, 04:15 PM
8683jb
I cast some .58 minie for my son-in-law, with the same problem. Best I remember I had to jack up the melt temp, get the mold pretty hot and tilt the mold and swirl the lead in, then had about 10% reject rate.

Good luck

milkman

Maven
10-11-2012, 04:32 PM
I recently bought a Lyman #575213-OS Minie bullet mould and am having a tough time getting pure-lead bullets to cast without a having cavity near the top of the hollow base. I've tried faster/slower pouring rate, tipping the mould, hotter/colder temp., still with about a 90% reject rate! What am I doing wrong? Thanks for the help!

Clean, polish and degrease the removable base pin/plug, then smoke it with a few wooden matches after a few trial casts. You do need more heat, especially for so large a casting: 800 deg. F. Btw, a good casting thermometer (not expensive) will help you maintain a consistent temperature and fewer rejects. Lastly, consider adding perhaps 1/2 [of one] % tin to your Pb to lower surface tension and better fill-out.

Bagdadjoe
10-11-2012, 04:33 PM
I had the same problem..little pin hole in the middle of the hollow base? I turned the heat up to almost max on my RCBS bottom pour, got the mold up close to the spout and tilted the mold when I started pouring. My mold had to be good and hot and I opened to spout up to get a really heavy flow out of the pot. Are you running pure lead or maybe like a 30-1 mix? A little tin will help and probably won't make too much difference in expanding the skirt of the bullet? There will probably be some argument on that last statement.
Use good ventilation if you are running the pot really hot, goes without saying I guess.

10 ga
10-11-2012, 04:34 PM
Dittos " " for what milkman said. I cast 69 and 50 minnies and 50 and 45 REAL and with the soft lead you need more heat in the melt and on the mold and I tap the mold as I pour and it takes more time to get the boolits to harden to dump so takes more time but that or a whole lot more culling. Best, 10 ga




x

Chicken Thief
10-11-2012, 05:01 PM
Most often the "problem" is letting the spout of lead hit the HB pin directly.
It will overheat (the tip) and then create a void in the lead just above the tip.

bob208
10-11-2012, 05:05 PM
this is why i am trying to swage them. that is the way they were made.

Stonecrusher
10-11-2012, 06:10 PM
If you are bottom pouring, try a dipper. I have always had more luck with BIG bullets using a dipper. Also I turn mold sideways and place the spout of the dipper into the cone of the sprue plate then turn both vertical to fill. Seems to work good for me.

Also, unless you are using these in the Olympics, I wouldn't worry too much about a little air cavity. I had the same problem when I started casting the same minie years ago and did a test on defects. Unless the cavity was very large, I kept them all and only culled those with a wrinkle on the bottom edge of the skirt. That was the only defect that had a noticable effect on accuracy. Any wrinkle on bottom edge went back into the pot.

8683jb
10-11-2012, 06:27 PM
Thanks for all help guys. I'm not sure of the exact makeup of the alloy but as far as I know it's pure lead, or pretty close to it. I've tried a dipper with similar results. No rhyme or reason either - one will come out perfect (at least it looks perfect) with no change in technique and the next few will be messed up. Anyhow, thanks again. I'll try your suggestions. And I agree with Stonecrusher - no better than I shoot, a little hole here or there in the boolit won't matter. Probably help!

Mk42gunner
10-11-2012, 09:31 PM
All the previous ideas can work. The thing I found helped the most was keeping the base pin hot; either by rigging a holder to keep it in the melt, or using a propane torch on it. The base pin spends a lot of time out of the mold blocks, cooling all the while.

Robert

Wolfer
10-11-2012, 09:47 PM
As stonecrusher said, I have the same situation with my 50 cal minis. They shoot as good as I can. Unless there's a wrinkle on the base or a big cavity they go down a barrel.

HARRYMPOPE
10-11-2012, 09:51 PM
dipper pour and let a full ladle empty in the mold.Pull away and top off just at the end and make a puddle and you wont get very many pinholes.I have been casting alot of 58 Minie's this last year for my Parker Hale .577 muskets and it has been working for me very well.With good light i have shot a few just under 2" five shot groups at 100 yards with those crude sights.

Cast with the pot at 800 deg also. and use as pure lead as you can find.

And have Erik Ohlen do this to your mold and life is much easier.

George

8683jb
10-15-2012, 09:00 AM
George -
Is that an aluminum pin?

44man
10-15-2012, 11:48 AM
I cast hundreds of .54 minie' balls for a friend and all were perfect.
I must have cast a few hundred thousand 12 ga slugs with no trouble.
But the few .58 Lyman molds drove me nuts. I tried everything, even cutting vent lines on the plugs, casting at every temp and technique.
I got to think there was an air pump in the pin that went BLURP :holysheep
It is a job for the ghost hunters!