PMA Tool

PMA Micro Adjust Trimmer

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  • PMA Micro Adjust Trimmer
  • PMA Micro Adjust Trimmer



The PMA Micro-Adjust Case Trimmer will trim nearly any bottleneck cartridge you can throw at it. Our trimmer indexes case length off of the shoulder of a properly fire-formed and full length re-sized case. We accomplish this through the use of interchangeable Delrin™ inserts which capture the shoulder and neck of the case. This insert is contained in a spring loaded tool head that rides on a linear bearing. When the case is captured within the tool head the tool head rotates along with the case, the spring allows for the case to self-align squarely to the cutter and allows you to control the feed rate into the cutter.


Our trimmer can be used in three ways. The first method utilizes our PMA Tool caseholder drivers and your power screwdriver, drill, case lathe, drill press or lathe. Trimming via this method the case is spun and fed into the trimmer while it is held in your hand. This method is handy in that the case is turning and the case mouths can be chamfered immediately after trimming rather than as a separate operation. In the second method, the trimmer’s adjustment knob is removed (after adjusting and locking the setting) and the cutting shaft is chucked in a drill, drill press or lathe. Using this method, the case itself is held by hand and fed into the cutter. We’ve found this to be the quickest method to trim, but does require case mouth chamfering to be done as a separate operation. The trimmer can also be used by hand. We have found this to be the slowest method of course, but will work in a jiffy if need be.



  • Indexes off shoulder for easy, consistent trim length
  • Fully rotating head with bearing for smooth operation keeps cuts square
  • Large, ergonomic design fits the hand well
  • Sharp carbide cutter for quick, smooth cuts with minimal bur
  • Cases captured in Delrin™ (completely non-marring material)
  • Spring loaded head allows complete control of rate of feed.
  • Can be used by hand, in conjunction with PMA Case Driving System and drill/power screwdriver or chucked in a drill, drill press or lathe.


The trimmer includes one cartridge family specific insert. Please choose from the table below and the drop down menu below that when ordering.


If you have a custom chamber and desire the best possible insert to cartridge fit, select the "Blank Insert" ("P") and ream the insert using the same custom reamer as your rifle's chamber. Blank Inserts have a 1/4" pilot hole pre-bored.



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2 Reviews

  • 5
    Micro Adjust Trimmer

    Posted by Victor Robinson on 17th Jan 2022

    Why did I wait so long to buy this! This is the easiest trimmer I have used to date, which did not cost the earth to buy. A little fiddly to set up at first, but once set up, easy to trim my brass and consistent. Well worth the cost, very happy.

  • 5
    Easy and Accurate Trimmer

    Posted by Steve on 3rd Feb 2016

    The trimmer is easy to use and not too difficult to set up. Chuck the brass, hold the trimmer in one hand and run the power drill with the other hand. You can feel the cutting vibration stop when the trimming is done. All the brass was trimmed to within .001 length. None of my other trimmers came close to this accuracy. Well worth the money.

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