Monitor Bullet Seating Force: K&M Precision Force Pack with L.E. Wilson Seating Die

Bullet seating force can tell you a lot about what’s going on with your reloads. Are you wondering if you have proper neck tension? Measuring bullet seating force can lend important insights. Consistency in bullet seating force can also have a big affect on the consistency of muzzle velocity. While this factor is important (seating force)- it’s also frequently overlooked.

While there are multiple ways to measure bullet seating force, there’s one method that’s both simple and effective: the K&M Precision Force Pack. This product works with the K&M bullet seating arbor press, and uses a dial indicator to read out instantaneous bullet seating force.

In order to use this setup you’ll need the following:

  1. K&M Precision arbor press
  2. K&M Precision Force Pack or Low Force Pack (with appropriate indicator)
  3. Wilson chamber-type seating die

Wilson Chamber-Type Bullet Seating Die

The L.E. Wilson Chamber Type seating die works differently compared to other seating dies. Most dies seat dies while there is relative motion between the case and the die body. The Wilson Chamber-Type seater holds the case stationary while a bullet seating stem is moved downward by means of an arbor press. In that way, more precise alignment is achieved between the case body and the bullet. That translates to less runout!

The arbor press that I use is from K&M Precision.

K&M Precision Arbor Press

The K&M Precision arbor press is a precision-oriented arbor press that’s meant to be operated by hand, and is optimized for operations like seating bullets.

From the product page:

  • Perfectly suited for use with in-line bullet seating and bushing neck die such as LE Wilson.
  • Compact size allows for use on your loading bench or at the range.
  • No need to permanently mount to your loading bench: however, mounting holes are provided if you wish to.
  • Press working height is adjustable from 0” to 7.5” or 0” to 6” when one of the force packs are used.
  • Height adjustment is made by loosening 2 screws on the right side of the press headwith the supplied T-Handle hex key.
  • 1” press ram stroke.
  • Easy height adjustment. Loosen the two press head clamp screws and place your die under the ram. Next stroke the handle fully. Now retract the handle so the head moves down 1-2 scale divisions and tighten the screws. This will give the proper height setting for most situations.

A Force Pack for Every Occasion

The “Force Pack” is an add-on for the K&M arbor press that enables the use of a dial indicator to monitor bullet seating force, and it comes in two varieties, “standard” and “low force”.

Standard Force Pack

The standard force pack (pictured above, left-hand side) is used with a .001″ resolution dial indicator. Each .001″ increment equals 1lb of force. Force range is 0-150lbs. This Force Pack will work for most bullet seating scenarios and applications. You can use any 0.001″ dial indicator with a 3/8″ stem and adequate travel with the Standard Force Pack. A compatible dial indicator is available on the K&M Precision arbor press builder page.

Low Force Pack

For more sensitive applications like Bench Rest reloading where bullet seating force is minimal, the K&M Precision Low Force Pack should be used (see above picture, right-hand side). A special dial indicator is sold that works with this Low Force Pack. This special dial indicator is calibrated to read in pounds force directly. The force range for the Low Force Pack is 0-50lb.

Installing the Force Pack

Installing the force pack is very easy. Here’s what you do:

  1. If needed, raise the arbor assembly in the frame to the top of its adjustment range
  2. Insert the rod end of the force pack from underneath the ram
  3. While holding the force pack against the ram, tighten the allen screw (key is included)
  4. Loosen the thumb screw at the top of the ram, insert the dial indicator down into hole
  5. Adjust the height of the dial indicator until the needle is pointing straight up
  6. Tighten the thumb screw
  7. Adjust the dial indicator dial to “zero out” the indicated value
  8. If needed, lower the arbor assembly until the bottom of the force pack is within about 1/8″ of the top of the Wilson seating stem (with cartridge + bullet in die)
  9. Seat bullets, read force while seating (each dash on indicator is 1lb)

The force pack can be removed in about 30 seconds. Very quick, and you may want to remove it while seating bullets when you don’t need to monitor seating force (it does change the “feel” when seating bullets).

When You Need This Tool

There are a few scenarios where having the K&M press and Force Pack is helpful including:

  1. Validating neck sizing setup (including when using expanding mandrels)
  2. Investigating how factors like annealing affect seating force and seating force consistency
  3. Quantifying how individual factors (like cleaning process or carbon fouling) affect bullet seating force
  4. Troubleshooting collapsed case shoulders, etc
  5. Verifying compressed loads and effect on peak seating force

Do you have a setup like this? Did I miss any of the common uses for this tool? Please let me know by dropping a comment! Look for more related stories coming up.

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One thought on “Monitor Bullet Seating Force: K&M Precision Force Pack with L.E. Wilson Seating Die”

  1. Great info! Would really like to see how you learn to mitigate the seating force difference in brass – a very worthy endeavor if you can pull it off and if anyone can it is you!

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