### Super-Wheelweight from Rotometals Superhard ?

Posted:

**Thu Sep 10, 2015 6:56 am**In search of the ultimate hard cast bullet for high velocity loads, I want to try making "Super-Wheelweight" with 6% antimony rather than the usual 3% antimony. Enter Rotometals "Superhard" ingot containing 30% antimony.

Formula for 6% antimony, assuming your clip-on wheelweight contains 3% antimony:

1 part Superhard

8 parts clip-on wheelweight

I also want to try boosting the arsenic and to that end I'll add reclaimed shot to the 6% alloy. Assuming that the 6% alloy contains 0.17% arsenic (NRA Cast Bullet manual page 127) and that the reclaimed shot contains 1% arsenic (typical but it varies tremendously) then the following mix would boost the arsenic to 0.3%, which I'm told is near optimal (NRA Cast Bullet manual page 126):

Formula to boost arsenic from 0.17% to 0.3%:

1 part reclaimed shot containing 1% arsenic

7 parts wheelweight or Super-Wheelweight

or Formula for 6% antimony and ~0.3% arsenic:

1 part Superhard

1 part reclaimed shot

7 parts clip-on wheelweight

Since we don't know the exact chemical composition of either wheelweight or relclaimed shot, these proposed formulas are not super precise but should get us in the ball park.

Formula for 6% antimony, assuming your clip-on wheelweight contains 3% antimony:

1 part Superhard

8 parts clip-on wheelweight

I also want to try boosting the arsenic and to that end I'll add reclaimed shot to the 6% alloy. Assuming that the 6% alloy contains 0.17% arsenic (NRA Cast Bullet manual page 127) and that the reclaimed shot contains 1% arsenic (typical but it varies tremendously) then the following mix would boost the arsenic to 0.3%, which I'm told is near optimal (NRA Cast Bullet manual page 126):

Formula to boost arsenic from 0.17% to 0.3%:

1 part reclaimed shot containing 1% arsenic

7 parts wheelweight or Super-Wheelweight

or Formula for 6% antimony and ~0.3% arsenic:

1 part Superhard

1 part reclaimed shot

7 parts clip-on wheelweight

Since we don't know the exact chemical composition of either wheelweight or relclaimed shot, these proposed formulas are not super precise but should get us in the ball park.