Problem with cast bullets 45/70

clone · Nov 27, 2019

The mold is a 405gr rnfp Lee bullet mold. The pot is a 20lbs Lee bottom pour. Coww for lead source. Brass is starline, sized and belled with Lee 3 die set. Lubed with Lee alox thinned with mineral spirits.

The problem is about half of the bullets dropped from the mold is slightly undersized. Enough that once loaded, I could press the bullets in with my thumb. Also 75% had rounded edges to the lube grooves.

My question is, is this a heat problem with the mold, or lead? Possibly a problem with my lead? I was casting outside in about 40 degree sunny day.

I have cast 32 and 9mm and never had this problem before, with maybe 5% to 10% rejects. But it was in warmer temperatures as well.

Any help would be appreciated.

Bob Willman · Nov 27, 2019

I haven't cast bullets for several years but my initial guess would be cold mold blocks chilling the lead before it fills out the mold cavity.

straight-shooter · Nov 27, 2019

I just received the very same mold last week. Same problem and i'm using wheel weight and soft lead with 2% tin. Has always filled molds for me like a charm, not with this one. They cast at .455, completely unacceptable for my 45/70. I threw the mold in the drawer and ordered a NOE 460-396 PB. The NOE mold is casting at .461 like it should. Lesson learned, buy once cry once.

Just in case your interested in the NOE 460-396. They are available in 2,3,4 and 5 cavity. Plain Base or Gas Checked.

http://noebulletmolds.com/NV/index.php?cPath=42_139&osCsid=0nh0drbt9himr27mael7s38i90

GooseGestapo · Nov 27, 2019

Two suggestions:

1. Clean mold, shim with aluminum ducting tape. Re-smoke mold with a butane lighter.
2. Add 2oz of Leadfree solder to pot. (95% Tin, 5% Antimony).

Additionally, size to .460 or .461”.

Arkansas Paul · Nov 27, 2019

I don't like using my bottom pour pots for large bullets like .44 and .45.
I do for small stuff like .357 and .40.
I have trouble every time I try to use the bottom pour for big ones.

25-20 WCF · Nov 27, 2019

I’ve used that mould number for over 30 years, it has always produced fine bullets for me. (Actually I started with the same number over 40 years ago but a friend damaged it and then Lee changed the design.). My metal is ww plus 2% tin, bullets come out at 0.4585”. My Lee bottom pour pot is run hot, indoors.

Perhaps Lee has again changed the design. Perhaps their cherry is worn out. Likely the lead is not hot enough or the mould is cooling off quickly in the cold air. Lee moulds are small and aluminum loses heat quickly, especially if you tend to cast slowly.

.

Slamfire · Nov 27, 2019

When I cast 510 grain Minie balls I found you have to run the lead hot. Four hundred grains of lead is a lot of lead and you need to crank up the heat until your bullets start filling out the mold.

clone · Nov 28, 2019

Can't cast indoors. I will try again on a warmer day.

Arkansas Paul,
What kind of problems do you have with bottom pour pots and large bullets?

GooseGestapo,
"shim with aluminum ducting tape". How exactly does that work.

MEHavey · Nov 28, 2019

1. The mould has not reached high enough/stable temp (use hotplate to pre-heat)
2. Get a thermometer, and cast as close to 710-720 as you can (colder = larger) consistent w/ fill-out in pre-heated mould
3. Contact pour using spout-equipped dipper.

flashhole · Nov 28, 2019

your mold is too cold

Reeferman · Nov 29, 2019

I use a Lee 10lb bottom pour pot casting with Lee 405 grain HB single bullet mold and Lee 500 grain double bullet mold and they come out at 461 to 463. That’s with 20 to 1 or 30 to 1 lead/tin at 750 degrees. Both of those molds are advertised as .459. Is the one you have a .457?
I use a propane torch to pre heat the molds and within a couple casts the bullets are coming out perfect.

Problem with cast bullets 45/70

clone

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Bob Willman

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straight-shooter

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GooseGestapo

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Arkansas Paul

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25-20 WCF

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Slamfire

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clone

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MEHavey

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flashhole

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Reeferman

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