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About Corbin Adjustable-Length Jacket Trim Die

The Corbin ET-2-R jacket trimming die, for use in slotted ram RCBS-type reloading presses, uses a tapered punch to expand the trimmed ring so is very lightly attached to the jacket where it can be flicked off by hand upon ejection of the jacket.


Here are some of the features and uses of the ET-2-R:

  • Jacket is the same diameter after trimming length
  • Nearly any shorter length may be obtained quickly
  • Trim takes place as punch enters the die mouth
  • Length is set with a stop screw adjustment
  • Stock jackets of a single length, use for lighter weights
  • Trim fired .22 cases (LR, Stinger, or 22 WMR) to precise length

The ET-2-R is normally used for drawn commercial jackets, made from a strip of copper or gilding metal. Copper tubing can be too difficult to pinch trim without the power of a Hydro-Press. Steel, hard brass or other unusual jacket materials should not be used without sending samples to Corbin for testing and evaluation. Doing so may damage the die or punch.

To operate, simply adjust the threaded stop screw at the top of the die so that the desired length of jacket is within the die body, and the surplus to be cut off projects from the die mouth. An adjustable depth gauge is provided with the die to aid in setting correct depth of the internal punch. Simply set the gauge for desired length, and then hold it in the die and bring the internal punch to touch the end of the gauge.

The punch pushes the jacket into the die. When the jacket head comes up against the end of the adjustable stop, the shoulder of the punch is driven further into the jacket mouth, expanding it. The expanded portion slips over the shoulder on the punch and is pinched nearly through against the hard die mouth. The surplus material is left on the punch as a cone of expanded metal that can be lifted off easily, or it is left very lightly attached to the jacket by a thin film, which separates easily by hand. Ejection of the finished jacket is done by tapping a knock-out rod in the top of the die, using a plastic mallet or short length of wood. The jacket ejects with light force; it is not necessary to pound the ejector rod. A neoprene 0-ring at the top of the ejector prevents it from falling through the die.

This trim method is faster and more precise than using a separate cutting tool such as might be found in a lathe or other rotating machine tool. Push the jacket in, press on the die handle, and the job is finished. In order to assure success, you must send a dozen sample jackets of the exact lot to be pinch trimmed. If you do not sent samples, then we must use our jackets, which may have different spring-back and stretching characteristics than yours. Therefore, although our trimmed sample jackets may show perfect conformity, the quality or dimensions of a randomly choosen jacket may show varying results with the same die. Aways send the sample jacket you will be using.

For faster, more automated operation in the Corbin CSP-1 press, Hydro-Press, Corbin CSP-2 press, or Hydro Junior, the ET-2 ram-mounted self-ejecting and self-stripping die set is recommended. This die does not require manual ejection of the jacket, and is faster to operate than the reloading press type. For high volume trimming, using special low wear materials, the ET-2-HC "commercial" version is a better choice.


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