Casting advise question

[Shriner]

Just started a new round of casting with a new batch of lead and the bullets are casting about 20gr lite. I checked the lead out in other modles , all casted lite. Should I dump the lead and start fresh or use it up and get fresh lead for next time? I have load data for the weight that is casting ,it's just not the weight I wanted cast up.

 

[rickm]

A lot of unknown variables but will take a shot at it, Depending on what lead your using sometimes adding some pure lead will get your weight up or casting at a lower temp will raise it.

 

[red dirt shootist]

If it were me, I think I would chunk it, but it also depends on how much you have. I can live with a lot of variables, but when I reload I like consistency. On the other hand, when your bullets fly all over the place, you have something to blame it on.

 

[rickm]

Really casting is like a Mad Scientist you have to play around to get what you really want and reach the outcome your expecting.

 

[TeamTomlyn]

What mold are you using? Have you cast with it before and hit the advertised weight? Got a hardness tester? Where did you source your lead?
I've had particular molds run lighter than advertised and different alloy mixes get me different weights, but never 20 grains worth of deviation. I have found a few old bullet molds that have been bubba modified and shaved down to produce a lighter bullet...

 

[Shriner]

All the models were light and in the past, they casted at or near weight .
They are a mix of Lyman and Lee .
I checked the hardness with my Saeco hardness tester and got 15/16 hardness.
The lead is a mix of wheel weights I got from a friend and Roto Metals SuperHard, the cold lead has a frosted look to it in the pot .
I think some Zinc weights may have been mixed in ?
I was trying with Lee 9mm 147 tc ,I have load data for 124 tc .
A full pot ,10lbs .

 

[TeamTomlyn]

Dang 15-16 Brinell is consistent with a mix of WW and HC... I was thinking if you were casting some big 45s and had a really high tin content could knock off some of your weight there.
I'm not sure if Zinc would throw your weight off that much. Unless in made it chunky enough to clog up the flow and leave a hollow space...
I mean worst case scenario you make a 10# anchor and try again with a new batch. I just cant imagine losing 20 grains on 147g mold.

 

[swampratt]

My Lee 2 cavity 357 mag 158 gr swc GC mold tossed 172 gr, bullets from clip on wheel weights.
When I melt wheel weights I sort all the zinc ones out.
When I had the blue color on top of the lead and tossed in some zinc weights they would just float and never melt into the mix.

You could find some pure lead and melt a small amount of it and fill the mold and compare the weights.

No matter what weight my bullets come out to i like to shoot them and see if i can make them accurate.