How to Use Case Trimmer [Step-by-step Guide Beginners]

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The Reloading process is pretty complicated in a way. This process requires patience and long time, as this process has some certain steps. You need to follow every step very carefully. These steps have some different parts. First, you need to take a bench, install a reloading press on the bench, then you need to work on the ammo cases you have.

To make your reloading process successful, you need to prepare your cases carefully.  That’s why this process takes a bit time and requires full concentration. If the cases aren’t prepared properly, then the cases could be jammed in the rifle chamber and cause serious damage. Which is pretty hazardous. Some essential steps need to be done for case preparations.

  • Case needs to be resized
  • Case needs to be trimmed
  • The case mouth needs to be deburred from outside
  • Inside of the case mouth needs to be chamfered
  • Primer needs to be cleaned

Today we will discuss case trimmer and trimming. When we shot ammo, the brass of the case flows forward due to the firing procedure of the round. That makes the brass case increase in length. Sometimes the cases get too long to fit in the chamber.  That’s why these cases needed to be trimmed. To trim these cases we need a tool, which is being called “case trimmer”.  There are so many different case trimmers out there. All of them are effective in their own way. You can use any of them.

How to use case trimmer

How to use case trimmerKnowing the correct method to use a case trimmer is very essential. If you cannot use the right method or correct tool the whole case trimming effort can go wrong. So, let us discuss the correct methods to use a case trimmer.

Step 1: Install Pilots and Collets in Case Trimmer

Install Pilots and Collets in Case TrimmerFirst, you need to choose the correct pilot and collet for the case trimmer. There are a cutter shaft and a collet screw in a case trimmer.  The pilot needs to be inserted into the cutter shaft and collet into the collet screw.

The Case of the ammo that you want to trim should be inserted into the.  Into the neck of the case, your pilot needs to be moved.  Then you need to push the case against the bottom of the collet. You can do that with a crank handle.

You need to make sure that the collet’s bottom is firmly holding the base of the case.  Also, ensure that inside of the case neck is being supported by the pilot.   You can then tighten the collet. There are some cutter teeth on a trimmer. You need to make sure that they are contacting the case neck.

Step 2: Make a trial cut to check case length

Make a trial cut to check case lengthBefore you begin the trimming process you need to make a trial cut. To check the accuracy of the case length, you need to make trial cuts. To do that make a trial cut with cutter teeth. After the cut is done, check and confirm the measurements.

To make a trial cut you need to turn the crank handle first. After the cut is done remove the case from the cutter teeth. Now you have to measure the length of the case.  For that, you will need an accurate scale. A caliper would be a great option to do that.

Now all you need to do is verify the length. A reliable reloading manual can tell you whether the case length is accurate or not.

Step 3: Make fine adjustments for case length and set stop collar

Case length and set stop collarThere is a collar stop adjustment screw on a trimmer. Turn that stop collar fine adjustment screw.  If you turn that properly that turn will be as equal as 0.032 inches. Now the question is in which way to turn. If you turn the screw clockwise, it will increase the case length. If you turn it anti-clockwise the case length will be decreased.  Continue the process until the case trimmer is well adjusted. When it is well adjusted, use the stop collar fine adjustment screw to lock the stop collar in right place.  Check the case length for the last time. Readjust if necessary.

Step 4: Begin your Case Trimming

Begin your Case TrimmingAfter seeing that everything is checked, now you may start your trimming. Before you begin to trim, always maintain the following steps.

Set up your trimmer to trim a batch of cartridges to the exact same length. Otherwise, all your efforts will go in vain.

Keep some light oil close to you.  Don’t forget to lubricate the cutter shaft to the bearing surface with a drop of it after a few moments.

After trimming correctly, save a master setup case and label it. This will help your future trimming a lot.


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Author - Hans Wimberly
Hans-Wimberly - the owner of Gearsadviser
When I`m not spending time with my beautiful wife and great 3 children, you will find me reloading ammo!
Doing sport shooting, or talking with my friends about (oh, yeah!) guns.

Read more about me here.

At Gearsadviser, I`m committed to ensuring that you have the best possible reloading experience. I conduct thorough research, testing, and evaluation of reloading gear, offering impartial and informative reviews to assist you in making informed purchasing decisions. My reviews are based on hands-on testing, research, and analysis of customer feedback. I regularly update my reviews to reflect changes in product availability and new information, so you can be confident that you're receiving the most current recommendations.

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5 thoughts on “How to Use Case Trimmer [Step-by-step Guide Beginners]”

  1. Can you use this kind of router to do deeper cuts? I need something to route out the insides of an electric guitar and don’t want to spend more than I have to. Any advice would be greatly appreciated. Thanks, and thanks for the video.

  2. One thing you did not mention and is aggravating is the standard base plate does not accept all 1/4 bits. I have a Craftsman set of bits, the Roman Ogee bit I use a lot, that will not fit through the base plate. Trying to find smaller bits or another base.

  3. I’m trying to freehand a hardwood cookie. I’ve got a dremel 4200 series and I think I have the right bit, but it starts burning before I get anywhere. Is there a certain bit I should be using, or am I just going to have trouble because I am working in the grain? I bought a carbide coated one, then got home and realized the shaft wouldn’t fit. Is it in a rpm thing? The 4200 goes up to 35k rpm. Do I need to buy a trim router specifically?

  4. can i use a 3/4″ straight bit to create a dado groove in a solid cherry slab with a palm router? I am sure a full size router would be more steady, but i want to know if this is something a small trim router can handle or is this just dangerous? thanks

  5. Can you please tell me where you obtained your earphones and what brand they are. My father has been looking for a pair like that and we haven’t been able to find a pair like that. Thank you

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