Skip to content

Forster Datum Dial Measurement System Body only with Screws


Notify me when back in stock

This Forster Datum Dial 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, a chart showing common datum diameters, instructions and a handy plastic storage box. (A caliper is required.)

Provides a relative measurement between the head of a cartridge 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 Cartridge Dials are available separately.

Also available as the Datum Dial Kit with Cartridge Dials #1 and #2 included.


  • Easily interchangeable dials: case and bullet/cartridge dials provide quick measurement of different calibres
  • Consists of only four components: provides the same calibre coverage as other products with many more components
  • Covers multiple calibres: competing products can require the purchase of a separate kit for each calibre 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

Datum Dial Aperture and Cartridge Suitability

A .330"
17 Rem; 204 Ruger; 22 Nosler; 220 Swift; 221 Fireball; 222 Rem; 222 Rem Mag; 223 Rem; 6mm x 45

B .350"
22 BR; 22 PPC; 22-250; 225 Win; 6mm BR; 6mm Dasher; 6mm PPC; 6mm PPC; 250 Sav; 6.5 Grendel; 300 AAC Blackout

C .375"
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

D .400"
243 Win; 260 Rem; 6 / 6.5 Creedmoor; 270 WSM; 7mm-08 Rem; 308 Win; 308 National Match

E .420"
264 Win; 26 Nosler; 6.5-284; 6.5 PRC; 7mm Rem Mag; 7mm Rem Ultra Mag; 7mm STW; 7mm WSM; 28 Nosler; 284 Win; 30-338 Win Mag; 300 Norma Mag; 300 PRC; 300 Rem Ultra Mag; 300 Win Mag; 300 WSM;
8mm Rem Mag; 338 Win Mag; 375 H&H

Datum Dial User Instructions