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Forster Datum Dial Ammunition Measurement System Complete Kit in Storage Box


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This Forster easy-to-use and versatile Datum Dial system is a ground breaking tool designed to gather the data you need to refine case sizing and bullet seating operations. Core components include a body and three dials that reliably measure relative distances between selected points on cases, bullets, and cartridges. Your payoff? Precise information that helps you increase accuracy, improve safety, maximize consistency, and boost your reloading capability.

The patented Datum Dial also works to measure bullets and cartridges, for use in adjusting the seater die to the optimum seating depth.

Provides the data you need to refine your hand loading:

  • Better accuracy because your ammunition’s headspace is tailored to your firearm’s chamber
  • Safer shooting because excessive headspace, which may lead to dangerous case separation, can be avoided
  • Quick sorting of batches of cases, bullets and cartridges to effectively remove variation to provide relative consistency
  • More reloads possible because of reduced work-hardening of brass

Easy-to-use ammo measurement system gives you the data you need to refine your case sizing operations.

This complete kit includes one Datum Dial tool for checking cartridge cases, both bullet/Cartridge dials for use with 17 cal, 204, 224, 243, 257, 264, 277, 284, 308, and 338 bullets, laminated chart showing common datum diameters, instructions and storage box.
(A caliper is required.)

Datum Dial User Instructions

Bullet / Cartridge dials are interchangeable and provide quick measurement of different bullet diameters and cartridges.

Bullet Dial #1

Bullet Diameters;
.224 Cal (5.56mm)
.243 Cal (6mm)
.264 Cal (6.5mm)
.284 Cal (7mm)
.308 Cal (7.62mm)

 Bullet Dial #2

Bullet Diameters;
.172 Cal
.204 Cal
.257 Cal
.277 Cal
.338 Cal

Blank Dial

(Five pilot holes in aluminium disc)


Aperture/Datum Diameter Cartridge Suitability

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

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