Modify Published Alloy?

[Eagle66]

I’ve had a problem with fill out with boolits from 2 different Lee molds. Parts of the bands have rounded edges instead of sharp edges like they’re supposed to.

http://castboolits.gunloads.com/attachment.php?attachmentid=93256&d=1389486204

I did the molud tune-up suggested in a post a while back. It helped, but I am still rejecting 45% or more of each run. I get better results, around 35% rejects, by running hot, ~700*. After sizing, the lube covers most of the defect. I’m using this alloy from a chart I downloaded:

Clip on WW, 9#
50/50 bar solder, 1#

Which comes out to approximately 5% Tin, 3% Antimony, Lead 92%, which is pretty close to Lyman #2.

So, I have two questions to put to the gang about this problem.

1. Am I being too picky? I mean, appearance is important, but the result that really counts is downrange, right?
2. Would adding 1%-2% more tin do any good?

Any help would be much appreciated.

[el34]

Classic wisdom says 1-2% tin for fillout, more than that is wasted. Long shot- are you letting the mold get pretty hot? If cold you can get voids. 700deg pot is not really all that hot, it's a reasonably good casting temp. Going hotter increases the rate of tin loss by oxidation.

For what it's worth I couldn't really see that much wrong with the boolit, maybe a little flaw in the top band?

[KYCaster]

You already have way more Sn than necessary. No need to add more.

Make sure the mold vents properly and pick up the pace to keep the mold hotter.

Jerry

[Certaindeaf]

I’ve had a problem with fill out with boolits from 2 different Lee molds. Parts of the bands have rounded edges instead of sharp edges like they’re supposed to.

http://castboolits.gunloads.com/attachment.php?attachmentid=93256&d=1389486204

I did the molud tune-up suggested in a post a while back. It helped, but I am still rejecting 45% or more of each run. I get better results, around 35% rejects, by running hot, ~700*. After sizing, the lube covers most of the defect. I’m using this alloy from a chart I downloaded:

Clip on WW, 9#
50/50 bar solder, 1#

Which comes out to approximately 5% Tin, 3% Antimony, Lead 92%, which is pretty close to Lyman #2.

So, I have two questions to put to the gang about this problem.

1. Am I being too picky? I mean, appearance is important, but the result that really counts is downrange, right?
2. Would adding 1%-2% more tin do any good?

Any help would be much appreciated.
Did you shoot them byatches? That's code.

[Certaindeaf]

Half painful but what you goin do? The price of tea in China is golly!? goot tlak

[sqlbullet]

No clue you experience level...but were I to guess I would bet you are looking at the bullets between casts. New guys I have taught always look at the bullets as they cast them. This allows the mold to cool while they gawk and then the next cast in the mold has rounded edges. Stop looking and cast with a good cadence. Inspect after you cast 100 or so and let us know if the reject rate goes down.

[Rooster59]

That's the first thing my casting mentor had to remind me of when I started. "Stop gawking and keep pouring."

[boog]

That was something I also found. Cast till the mould is too hot, then as you let it cool you can look through the boolits, then get back to casting!

At first, it sure is hard to not stop to admire/critique them.

[bangerjim]

Are you ladle casting or bottom pouring? makes a difference as to comments/feedback. Let us know.

But all above are good points to consider! 1-2% is MORE than enough tin!

Three words for casting good slugs.....temperature....temperature.....temperatu re.

bangerjim

[Eagle66]

I do ladle casting. And, yes, I have to admit I have been looking while I am casting. :oops:

Guess it's like "Ya never look at yer boolits while you're standing at the melter, there'll be time enough for looking when the pouring's done." (With apologies to Kenny Rodgers' song The Gambler)

[mold maker]

Cast them as fast as ya can till they are frosted. The slow down a tiny bit. The frosted ones will shoot just as good as the bright shiny ones, or maybe better.

[williamwaco]

Are you ladle casting or bottom pouring? makes a difference as to comments/feedback. Let us know.

But all above are good points to consider! 1-2% is MORE than enough tin!

Three words for casting good slugs.....temperature....temperature.....temperatu re.

bangerjim


Correct!

Three more words:

Cadence . . . cadence . . . cadence.

To maintain a constant temperature, you must maintain a constant cadence.

[el34]

Trying to state things in measurable terms-

1-2% tin is a good thing for mold fillout. More than that won't hurt anything, and it adds a small amount of hardness (about 0.3BHN per %) but tin is expensive and most folks use it only for that 1-2%.

A casting temp of 700deg is generally pretty good and works in most circumstances. Hotter and the tin starts to oxidize, colder and mold temp and pour rate become even more important.

But mold temp is important all the time. If too cold, boolits can/will get voids in them. Too hot, or maybe the point of approaching too hot, boolits will be frosty. That's ok, it's just an indication that the mold is plenty hot enough. Another way to tell is it seems to take considerably longer than normal for the sprue to solidify and when you slice it off the lead feels like peanut butter.

The cadence thing is to attempt to keep the mold at a happy temp. Too fast and it'll keep getting hotter, slower and it'll cool down.

You'll get going, establish a great groove pumping out great boolits, then realize you gotta pee.

[boog]

You'll get going, establish a great groove pumping out great boolits, then realize you gotta pee.

That is funny but true!

[fryboy]

of note i sometimes get rounded bands ( or even sides of boolits ) when casting too hot , i'm guessing that for whatever reason i get a hotspot in that one area and bam it's like the molten alloy shrinks from that area ( so in essence too cold or too hot can be problematic )
also sometimes with a new lee mold i'll have one problem area even tho i've cleaned it several times and even resorted to smoking it with no luck , in those cases i'll take a plain sharpened #2 pencil and shade the problem areas , sometimes it helps and sometimes it doesnt [shrugz]
as for quality control ... that can be as different as we are , i've found that the more culls i get per batch the lower my standard seems to slip to - especially if i'm just casting plinkers , some guys never worry about a few wrinkles and some guys reject a casting even at the thought of one ( i'm usually somewhere in the middle lolz )

[454PB]

Scrub the mould cavities with Comet cleanser and a toothbrush, spray with degreaser (brake cleaner works), preheat and cast fast.