P. O. Ackley Micrometer Reamer Stop

40070d47 P5500170

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(Third image shows parts separately; also shows assembled product.  Price is for one set of 5 parts with 5 set screws included.  Chamber Reamers sold separately.)

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Items that are in stock will ship within 7 days. If not in stock, this item is custom made to order.



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Precision, repeatability, and ease of use: these are the benefits of P. O. Ackley Micrometer Reamer Stop. Now you can do production runs with your Chamber Reamer, without having to index each workpiece axially. You'll be assured of consistent headspace, chamber after chamber!

To set up, insert your Chamber Reamer shank in the Reamer Holder and tighten the two set screws. Then insert the reamer holder into the Stop Cylinder assembly (micrometer threaded Stop Cylinder with .001" Adjustment Nut, Lock Nut and optional Plug Nut). Make a rough cut in the chamber (leave about .025" extra material). Now, with the reamer bottomed in the rough chamber, move the Stop Cylinder assembly into contact with the workpiece and secure it to the Reamer Holder with three set screws.

You can now adjust the depth of the finish cut in increments of .001", or even less. The Adjustment Nut is marked with 25 equidistant markings around the circumference, each of which corresponds to .001" of axial adjustment. By backing off the Adjustment Nut and re-securing the Lock Nut, then repeating the cut, you can zero in on your specified headspace measurement. Adjustments of .0005" can be made with confidence.

Once you've completed the first workpiece, your Reamer Stop will assure equal headspace in subsequent chambers without re-adjustment or axially indexing the workpiece.

The P. O. Ackley Micrometer Reamer Stop consists of the following:

  • One precision-ground Reamer Holder to fit a standard Chamber Reamer shank (two set screws included)
  • One precision-honed Stop Cylinder with 40 TPI micrometer threads (three set screws included)
  • One Adjustment Nut with internal micrometer threads and .001" axial adjustment marks
  • One knurled Lock Nut with internal micrometer threads
  • One knurled, threaded, AR Extension Stop (not always used, depending on Chamber Reamer configuration)

We recommend use with our floating reamer holders for best results.