.223 Rem / 5.56 x 45 mm NATO Case Trimmer and Shoulder Length Measurement Tool

One simple case trimmer to trim your .223 Remington / 5.56 x 45 mm NATO case necks to length and also measure/compare the shoulder length ie. headspace.

Works with any 8 mm or 5/16” cutter, end mill, drill bit, etc. As long as it is sharp. A simple HSS end mill can be included in the order.

Use as a case trimmer

1. Insert the end mill into the trimmer body, do not tighten the screws yet.
2. Pick out a regular empty case with the correct overall length (generally around 44.5 mm or 1.75” for .223/5.56).
3. Place the case into the body and push the end mill against the case neck and then tighten the screws. DO NOT OVERTIGHTEN.
4. Attach the end mill shank into a cordless drill or a drill press. The “fast speed” setting generally works well for cordless drills.
5. Trim the case by rotating the drill and feeding the case into the trimmer. Only light force is required to feed the case, however you do need to have a secure grip on the case (gloves recommended).
6. You will feel when the case shoulder butts against the case trimmer body and the end mill no longer cuts, this is a sign that the case is trimmed.
7. Check the lengths of the trimmed cases. If you notice that they are too short it is a sign that the trimmer body is sliding on the end mill. Reset the end mill position and tighten the screws in small increments until the trimmer no longer slides.
8. Periodically check the lengths of the trimmed cases to make sure that the trimmer isn’t sliding on the end mill.

Use as a shoulder length comparator

1. Attach the comparator body to caliper jaws by first sliding it on, squeezing the jaws shut with the body in place, and while holding them shut tighten the screws. DO NOT OVERTIGHTEN.
2. Pick out a case with a shoulder length you want to reference to, a reference case. This can be a case that you know has a good length or a headspace gauge etc.
3. Insert the case into the comparator, close the caliper jaws on the case, and zero the caliper.
4. Now when you test cases you will get a reading that shows the length of the case compared to the reference case.

Take note that cratered primers etc. will give you faulty shoulder length readings, consider first depriming the cases.

Durability

The comparator body is 3D printed from PETG which was chosen for its low friction characteristics. When used properly this trimmer will trim thousands upon thousands of cases without problem. Note that you don’t need to trim cases every time you reload them, especially if you aren’t sizing them too much, meaning that this tool will last you a very long time.

All Masiinatek products come with a five year warranty for any breakages occurring from normal usage.

Made in Finland.

If you’re ordering from outside the EU you may have to deal with the customs and pay VAT in your own country.