Brownells' Cerrosafe Expansion

[TexasMac]

Due to a discussion on this subject on another forum I contacted Brownells yesterday to check the accuracy of the expansion noted in the instructions that came with the Cerrosafe. I had preformed several experiments to check the expansion over time. Brownells literature indicated the expansion after 200 hours was 0.0025% (not inches but percent), and what I had found was 0.5%, a very big difference. I therefore assumed that Brownells had a typo in their instructions and actually meant to say 0.25%, which was still off my measurements by a factor of two. So I called and checked with one of their knowledgable technicians. It turns out the Brownells brochure is in error. The correct expansion is 0.0025" (read inches not percent). This concurs with the results of my experiment, which resulted in my determination of 0.5%. Using a bore of 0.5" (50 caliber), this amounts to exactly 0.0025" of expansion, the same as the Brownells' technican provided.
Wayne

[savageT]

Due to a discussion on this subject on another forum I contacted Brownells yesterday to check the accuracy of the expansion noted in the instructions that came with the Cerrosafe. I had preformed several experiments to check the expansion over time. Brownells literature indicated the expansion after 200 hours was 0.0025% (not inches but percent), and what I had found was 0.5%, a very big difference. I therefore assumed that Brownells had a typo in their instructions and actually meant to say 0.25%, which was still off my measurements by a factor of two. So I called and checked with one of their knowledgable technicians. It turns out the Brownells brochure is in error. The correct expansion is 0.0025" (read inches not percent). This concurs with the results of my experiment, which resulted in my determination of 0.5%. Using a bore of 0.5" (50 caliber), this amounts to exactly 0.0025" of expansion, the same as the Brownells' technican provided.
Wayne

Velly Intellesting........If Cerrosafe expands, how the devil do you get the stuff OUT of the bore or chamber???  Doesn't it contract as it cools?

[TexasMac]

Hello SavageT.  It sure does contract, but only for a relatively short time, which allows you to remove it from a chamber.  If you wait longer than 30 minutes to remove it you may have to remelt it in the chamber.  After one hour it's back to the original size and will slowly expand till around 100 hours or so, at which point it will stabalize with no further expansion.

I recently received the following information from a poster on another forum who had contacted the manufacturer.

"According to the maufacturer, Cerro Metal Products the expansion in inch per inch is as follows:
2 minutes -.0004, 6 minutes -.0007, 30 minutes -.0009, 1 hour .0000, 2 hours +.0016, 5 hours +.0018, 7 hours +.0019, 10 hours +.0019, 24 hours +.0022, 96 hours +.0025, 200 hours +.0025, 500 hours +.0025."

So the ideal time to measure the cast without any errors is close to 1 hour.
Wayne