Author Topic: Hardness  (Read 823 times)

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Offline jwp475

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Hardness
« on: July 28, 2011, 07:08:23 AM »
 
 
  Mr. Smith what is the difference in hardness between a water quenched bullet cast from wheel weights and one that is air cooled
 
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Offline Veral

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Re: Hardness
« Reply #1 on: August 01, 2011, 09:31:29 PM »
Water quenched WW can range from 20 bhn when the water is at room temp, and on some occasions up to 30 bhn, if the water is close to freezing and held at that temp for about 24 hours.  Putting the cold quenched bullets in a fridge during the 12 to 24 hour hardening cycle  will normally get you at least 25 bhn.

  Air cooled hardness will maximize in about 2 weeks after the cast and can vary from a low of 10 bhn if the casting is done in hot weather and bullets not kept spread out while cooling,  up to 12+ if cooled at about room temp and kept well spread out.  Best hardness I've obtained with air cooled, and my favorite way to make hunting bullets for rifles, is to cast only when air temp is 40 to 55 deg, and while keeping them well seperated on the pad, blow a small fan accross them.   14 and up to 16 bhn is possible this way.

  Ingots cooled in a hot mold will have a max hardness of around 8 after aging, which will be the hardness when casting by all the above methods immediately after the cast.  In other words, if you should want to make up a slug for getting a throat or groove impression, cast the blank, work it to shape and use it within about 1-2 hours after the cast and it won't be formidibly harder to work with than pure lead.
Veral Smith