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An interesting simple casting experiment
03-29-2019, 04:30 PM
Post: #1
An interesting simple casting experiment
I knew that the alloy temperature affected bullet weight but had never determined how much. Normally I went with the temp that resulted in fully filled out bullets using a specific alloy. Since I planned to cast sufficient bullets for 3 silhouette matches I figured I’d run a simple experiment. So I just finished casting & weighing 3 batches (60 bullets/batch) of .40cal 400gr bullets using the BACO 409400M5 (old 409400M4) mould and the RCBS Easy Melt PID controlled furnace.

The 1st batch was cast at 765 degrees & weighed 400.0grs +/- 0.6grs. The alloy temp. was increased to 770 degrees for the 2nd batch which weighed 401.0grs +/- 0.3grs. So then I lowered the alloy temp. back to 765 degrees for the 3rd batch with dropped back down to the same weight as the 1st batch (in this case the weight was 400.0grs +/- 0.5grs). So now I know that 5 degrees will result in a change of approximately 1gr.

BTW, the alloy was verified as 15.7:1 by measuring the specific gravity using a laboratory grade high precision scale.

Wayne

NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF (National Shooting Sports Foundation) Member, Author/Publisher of the Browning BPCR book.
http://www.texas-mac.com
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03-29-2019, 07:29 PM
Post: #2
RE: An interesting simple casting experiment
Intersting.
Did you cast all three batches on the same day?

A wise man can always be found alone. A weak man can always be found in a crowd.
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