Guns and Gear

Creedmoor Sports Introduces Shoulder Datum Tool

Creedmoor Sports continues to expand their lineup of reloading tools with the new Shoulder Datum Tool. When used with calipers, it can provide a comparative measurement of shoulder setback after sizing. This tool has six separate openings that allow measurements of 79 SAAMI calibers.

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This device does not provide an absolute measurement like overall length, but rather a comparative measurement. A piece of brass could be measured before and after sizing to show the change in the location of the shoulder. The Shoulder Datum Tool is in stock as of writing with a price of $49.95. You can find it at Creedmoor Sports.

The Shoulder Datum Tool clamps onto a caliper jaw, and the piece of brass sits inside the tool and against the other caliper jaw.


Creedmoor Sports Introduces Shoulder Datum Tool

The six openings of varying sizes are compatible with 79 cartridges.

From the manufacturer:

Measure your shoulder datum with the NEW Creedmoor Sports Shoulder Datum Tool!

Sometimes you just want to bump the shoulder back .002 to .003 to preserve brass life while still ensuring it will feed in your rifle. It can also help with accuracy in some cases if the shoulder is already touching the inside of the chamber.

It can also be helpful to know how the brass stretches during firing. If it’s being stretched a lot, especially in a bolt gun, this can mean the headspace may be excessive, or that the bolt isn’t making firm contact on the lugs.


  • Precision machined in the USA
  • Stainless steel
  • Mounts to calipers for one-handed use
  • Shoulder datums directly correspond to 79 SAAMI cartridges
  • Recessed measuring surfaces are protected from accidental drops or rough handling
  • Measures shoulder bump on most CIP, SAAMI and wildcat cartridges

All images from Creedmoor Sports

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