Easy-to-use ammo measurement system gives you the data you need to refine your case sizing operations. Includes one Datum Dial tool for checking cartridge cases, chart showing common datum diameters, instructions and storage box. (A caliper is required.)

Provides a relative measurement between the base of a case to a datum point on its shoulder angle. May be used:

  • Before sizing operations to find the optimal headspace for your firearm
  • After sizing operations to check the setup and consistency of your reloading process

Cartridges available separately. Also sold is the Datum Dial Kit with Cartridge Dials #1 and #2 included.


  • Easily interchangeable dials: case and bullet/cartridge dials provide quick measurement of different calibers
  • Consists of only four components: provides the same caliber coverage as other products with many more components
  • Covers multiple calibers: competing products can require the purchase of a separate kit for each caliber needed
  • Measurement is exact variation: no need to subtract body plus bushing/insert length from each measurement
  • Durable plastic storage box: room for extra setup, keeps all components together and protected
Cartridge Case/Caliber Usage Chart

Cartridge Case/Caliber Usage Chart

Aperture/Datum Dia. Case Caliber


17 Rem; 204 Ruger; 22 Nosler; 220 Swift; 221 Fireball; 222 Rem;
222 Rem Mag; 223 Rem; 6mm x 45


22 BR; 22 PPC; 22-250; 225 Win; 6mm BR; 6mm Dasher; 6mm PPC;
6mm PPC/Wild; 250 Sav; 6.5 Grendel; 300 AAC Blackout


6mm GT; 6mm Rem (244); 6mm XC; 25-06 Rem; 257 Roberts;
6 x 47 Lapua; 6.5 x 47 Lapua; 6.5 x 57 Mauser; 6.5 x 55; 270 Win;
7 x 57 Mauser; 280 Rem (7mm Exp); 30-06 Springfield; 30-30 Win;
300 H&H Mag; 303 British; 30-40 Krag; 32 Win Spec


243 Win; 260 Rem; 6 / 6.5 Creedmoor; 270 WSM; 7mm-08 Rem;
308 Win;308 National Match


264 Win; 26 Nosler; 6.5-284; 6.5 PRC; 7mm Rem Mag; 7mm RUM;
7mm STW; 7mm WSM; 28 Nosler; 284 Win; 30-338 Win Mag;
300 Norma; 300 PRC; 300 Ultra Mag; 300 Win Mag; 300 WSM;
8mm Rem Mag; 338 Win Mag; 375 H&H
Weight 0.70000 lbs



Sales Sheet
Datum Dial at YouTube.com
Datum Dial Switching Dials at YouTube.com
Datum Dial Assembling to Your Calipers at YouTube.com
Datum Dial Bullet Measurement at YouTube.com
Datum Dial Ammunition System at YouTube.com
High-resolution Images
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