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Rifles, Reloading, Optics, Equipment
Reloading
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<blockquote data-quote="CatShooter" data-source="post: 1306867" data-attributes="member: 7"><p>When the fad of measuring case head expansion with blade micrometers emerged from the swamp of ignorance came to light, I was one of the original Dumb Bunnies that ran out and bought one - a new top quality Starrett (cuz who would be dumb enough to have a used one in stock).</p><p></p><p>But I quickly learned the folly of my new toy... well not so quickly, cuz it caused me to waste a lot of time and bullets.</p><p></p><p>The problem is, case heads vary in hardness, A LOT!!!</p><p></p><p>Lapua, and Lake City cases have heads with a Brinell hardness (scale "B") around 80 to 90 (I measured them)... Remington and Hornady run 45 to 50-ish (I measured them too). </p><p></p><p>So, a load that is fine in your Lapua, LC, or Norma cases, will squish the heads of Remington and Hornady cases, giving your nifty blade micrometer a heart attack... yet the loads are fine and safe.</p><p></p><p>The second problem with using case head expansion for a "pressure indication" is that the pressure actually "thumps" the case head with 3,500 to 5,500 pounds (real pounds, not psi) of pressure, so each reloading, increases the hardness of the head.</p><p></p><p>Anyone wanna buy a nifty new (almost) Starrett 0-1" blade micrometer? Hardly used, in a beautiful case.</p></blockquote><p></p>
[QUOTE="CatShooter, post: 1306867, member: 7"] When the fad of measuring case head expansion with blade micrometers emerged from the swamp of ignorance came to light, I was one of the original Dumb Bunnies that ran out and bought one - a new top quality Starrett (cuz who would be dumb enough to have a used one in stock). But I quickly learned the folly of my new toy... well not so quickly, cuz it caused me to waste a lot of time and bullets. The problem is, case heads vary in hardness, A LOT!!! Lapua, and Lake City cases have heads with a Brinell hardness (scale "B") around 80 to 90 (I measured them)... Remington and Hornady run 45 to 50-ish (I measured them too). So, a load that is fine in your Lapua, LC, or Norma cases, will squish the heads of Remington and Hornady cases, giving your nifty blade micrometer a heart attack... yet the loads are fine and safe. The second problem with using case head expansion for a "pressure indication" is that the pressure actually "thumps" the case head with 3,500 to 5,500 pounds (real pounds, not psi) of pressure, so each reloading, increases the hardness of the head. Anyone wanna buy a nifty new (almost) Starrett 0-1" blade micrometer? Hardly used, in a beautiful case. [/QUOTE]
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