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I know it's been discussed here before.
Just can't find it.
Should be a sticky.
Right after casting, after a week or so, do they grow or shrink?????
I cast up some Lee 356-120 TC tonight.
They measure out at 357-358.
Will they shrink or grow after a week????
No need for a sticky.
Depends if you let them cool on their own or if you water cool them. My experience and my hardness tester tells me they change and part of this cycle seems to depend on the alloy and the conditions. Are they subject to being kept in a 50 degree room or 102 degree room. Generally I simply look at them and take a few to test the hardness and if they are what I am looking for I use them without worrying about if the hardness will change in 6 months or 3 months. To be blunt it really doesn't matter.
Perhaps reading thru some of these topics below will help you out.
The way I understand it is that different alloys have different "shrinkage/growth" based on their contents, as well as some that do not change much at all if any.
http://castboolits.gunloads.com/show...t-casting-size
http://castboolits.gunloads.com/show...-a-Cast-Bullet
http://castboolits.gunloads.com/show...ullet-diameter
I think its a product of alloy used, length of storage, temperature of storage.
Here is another place to look around for your questions:
http://www.lasc.us/castbulletnotes.htm
Halfway down the page there is this chart:
Alloy shrinkage of cast bullets
Composition, % Brinell Shrinkage
Type Metal Tin Antimony Lead Hardness Linear, %
Linotype 4 12 84 18 .65
Monotype 9 19 72 26 .65
Lead -- -- 100 5 1.13
Tin 100 -- -- 7 .90
Antimony -- 100 -- 50 .47
As an example: the solidification of a nominally .357" diameter bullet cast of Linotype could be expected from the above table to be .0065 X .357" = .0025". In a soft alloy of lead and tin, .01 X .357" = .0035".
Shrinkage - Bullet Diameter, Inches
Alloy .308 .357 .452
Linotype .002 .0025 .003
Lyman # 2 .0025 .0025 .0035
Soft Lead .0035 .004 .005
From the above two tables it can be seen that the softer the alloy and the larger diameter the bullet that more shrinkage will occur.
Bullet alloy as-cast & final dia. sized (.308 sizing die)
At the time of casting, the alloy will determine how much cooling shrinkage occurs. When sizing the bullets down, and during storage, the hardness (alloy) seems to be a factor in how much rebound to the original cast bullet size as well as grain development is a factor in "growth". Unless your bullets are dangerously snug in the throat, this is not really something to be concerned about.
This is shrinkage from actual mold size as when the alloy cools inside the mold and becomes solid. OP was talking about boolits growing in size after casting.Quote:
Originally Posted by JBinMN
Good info but it's a different issue.
They grow but not a significant amount, bullets containing some copper in the alloy seem to grow more.Quote:
Originally Posted by abunaitoo
Thanks for filling me in.Quote:
Originally Posted by Mal Paso
I guess I misunderstood him. Long night of pain, little sleep. I prolly should not have posted. Was just tryin to help out.
No worries! I think 2 issues were mixed from the start. I've never heard of a boolit shrinking after casting, only growing in size.Quote:
Originally Posted by JBinMN
I have ten years old .501 boolits that are .503-.504 now. They are NOE 425 grainers, they dropped max .0502 at the time of casting. I'm having a hard time sizing them now.
Very high antimony,they are 50/50 mono/WW.
I have no idea what the alloy is.
Most was range pick up.
Some wheel weights.
Some lead blocks used for counter weights.
I'm guessing I won't know unless I measure at different times.
Thanks
If I need a larger bullet, I dissolve vi-ag-ra in some water, and soak the bullets. They only stay bigger for four hours, so you do need to shoot them fairly quickly.
An idea; measure, weigh, and check hardness on your newly cast bullets. Record the results in your casting log. At one week, take a sample and repeat measurements, and record in your log. Continue weekly or monthly tests for 6 months and tell us what you get, along with alloy, temps, ambient conditions etc...
I normally measure and weigh my bullets after they cool. Mostly to see how the mold/alloy/temps are working together. Since on some later date they will be sized, as long as they are OK after the first check, they are keepers...
If you can detect any measurable difference from a boolit freshly dropped from the mold (after it's cooled enough to do so), to a week old boolit...Let us know.
I never noticed any change in size from aging, until you get to plenty of age, like a year or more.
OH, I've never seen one shrink.
OP wasn't asking about harness of the "gun"... ;)Quote:
Originally Posted by waksupi