Ejector pins commonly produce ejector marks on the. 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.Īnyone wanna buy a nifty new (almost) Starrett 0-1" blade micrometer? Hardly used, in a beautiful case. Ejector pins are metal rods in the ejector half die that push the finished casting out of the open die. Tighten the inserts or other loosen parts, eliminates improper embossings. check the condition of assembly parts of mold. adjusts the pushing bar to the correct position, repairs or replaces the pushing bar. checks the pushing bar state and dimension. 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. How to improve ejector pin marks in die casting 1. Remington and Hornady run 45 to 50-ish (I measured them too). Lapua, and Lake City cases have heads with a Brinell hardness (scale "B") around 80 to 90 (I measured them). Molding process conditions: Due to the characteristics of the molding process, ejector marks are inevitable on molded products, but the appropriate control of process conditions is able to. However, for the topography measurement of the ejector marks, the SRM cartridge case was tilted approximately 20 so that the principal surface of the ejector. The problem is, case heads vary in hardness, A LOT!!! If you are using a book load that is listed as mild then perhaps the brass is too soft. A mild overload will produce a shiny round mark on the case head. It is difficult to push sample out of the mold. + Sample doesn’t have a draft angle at boss, rib. ejector marks injection molding Cause of ejector mark. Samples are stick in the mold under force of ejector system, it will create holes on products. With many modern rifles, the ejector is spring loaded. In injection molding process, ejector marks is a concave or a convex on the surface. Some of the more common striated action marks include chamber marks shear marks, firing pin drag marks, extractor marks, and ejector marks. well not so quickly, cuz it caused me to waste a lot of time and bullets. There are signs to look for with mild overloads. 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).īut I quickly learned the folly of my new toy. Ejector marks are usually small marks or indentations on the base of the cartridge case made when the case is extracted and kicked out of the action by.
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