Too much thinking, just cast & sort them in 2-grain range lots and go shootin'!

Two days ago I cast 200 pcs of .458 Lyman 535 Postels. Average weight using 20/1 commercial alloy was 533.2 grains. Most were within 2 grains of each other, with the exception of 5-pcs. which were up to 4 grains lighter than the rest, and 1-pc. which was 2 grains heavier than all others. Had some issues with casting temperatures... ranged from 780 to 830 degrees, which I attribute as the cause of weight variance.

I'm not too sure about how much actual difference this much variance has to accuracy (except perhaps for long range shooting).  However, I sort the bullets in 50-pc. groups not exceeding about 1 grain total difference from high to low, and arrange in order from high to low. I don't keep bullets in order of cast... simply by weight.

Casting 420 grain .411 bullets from a Paul Jones mould, I have noted that bullet weight fluctuations are not as great as those dropping from one of several Lyman moulds.

Glenn

i think you might be worrying about the wrong sort of details.  There are many reasons for little changes in weight.  Even the time you take between each casting can lead to changes in weight from round to round. A sticky one that takes a bit longer to remove from the mold can lighten the next bullet you make.

I find it easiest to weigh each bullet when I am finished casting and sort them into lots within 1 grain of each other.  Most rounds will be sorted into two groups.  Anything that weighs outside the norm I throw into a bucket to melt and cast again.   

If you work too much on the process, you may find the product harder to create.

shovel80 wrote on Nov 22^nd, 2013 at 11:18pm:


Good.  a) there is someone else in the world that weighs right out of the mould.  b) you are shooting in the order cast as I did here (don't know yet if that makes a difference).  c) does within 0.4gr mean +/-0.4gr from the average?  Or +/- 0.2gr from the average?  In either case, I see room for me improving the variation in weight.

GlennM wrote on Nov 22^nd, 2013 at 11:15pm:


You raise some good questions here.  Mould brand A vs B.  I'm using one mould here, but what you brought to light is the question with the mould why variation occurs.  I need to examine the two or three things (loose sprue plate, alignment pins and/or clamping pressure) to see if they are causes of variation.

You also raise casting temperature.  Hmmm.  That brings up as well variation in flow from the nozzle and the several other techniques of filling the mould.

westerner wrote on Nov 22^nd, 2013 at 10:38pm:


I am among Joe B's Noodlehead Alumni. 

To me the act of shooting bullets as cast is to minimize the variation. If the lead temperature is same from bullet to bullet, you stand to minimize variation. Fill your mould in the same manner. Try to leave the same amount of lead on the spru plate. In other words , be consistant in your casting. Then I weight the bullets and sort by weight. To me, weighing the bullets is an indicator. Consistant weight, tells me my process is working. 
Kurt