Modular Headspace Comparator Kit
Modular Headspace Comparator Kit

Modular Headspace Comparator Kit

Short Action Customs
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Modular Headspace Comparator Kit comes with a pick of any 4 Modular Headspace Comparator inserts or bullet inserts, both short and standard body's, and a stand.  

Headspace Inserts for your Modular Headspace Comparator

The Modular Headspace Body must be purchased separately and can be found at the Modular Headspace Comparator Body page here.

New Modular Design for the most accurate cartridge headspace and bullet measurements available!

Newly designed Modular Headspace Comparator (MHC) is an updated version of our highly successful dedicated Headspace Comparator that we previously made out of 6061 aluminum.  We improved on its design allowing the new MHC to be used with cartridges up to 338 Lapua Magnum and more. 

 Each bullet and headspace insert is precision machined out of 17-4 Stainless Steel for increased durability and corrosion resistance. 

Modular Headspace Comparators will ship with your headspace comparator insert of choice by selecting the correct insert from the drop down menu. 

Bullet comparator inserts available shortly. 

***Please E-mail us at if you need a custom Headspace Comparator***

Please Use This Compatibility List To Determine Which Headspace Comparator Is Right For You. The Headspace Comparator Model Is Listed First, The Compatible Cartridge Is Listed After. 


223 Model

  •  223 Remington and 5.56mm NATO
  •  Wildcat Cartridges necked down from the 223 Remington. 

22 Cal x 40°

  • 223 Ackley Improved
  • 22-250 Ackley Improved

6mm x 20°

  • 243 Winchester
  • Wildcat Cartridges necked down from the 243 Winchester

6mm x 30°

  • 6mm Creedmoor
  • 6XC
  • 6x47 Lapua
  • 6BR
  • 6BRX
  • 6mm Super LR

6mm x 35°

  • 6GT
  • 6mmx284 Win

6mm x 40°

  • 6mm Dasher
  • 6BRA (6mm BR Ackley Improved)
  • 243 Ackley Improved

6.5mm x 20°

  • 260 Remington
  • 243 Winchester

6.5mm x 30°

  • 6.5 Creedmoor
  • 6.5 PRC
  • 6.5 SAUM
  • 6.5x47 Lapua

6.5mm x 40°

  • 260 Ackley Improved
  • 6.5mm Wildcat cartridges with a 40 degree shoulder

7mm x 30°

  • 7mm SAUM
  • 7mm Creedmoor
  • 7mm LRM

7mm x 35°

  • 284 Winchester
  • 7mm WSM
  • 7mm/300 WSM

30 Cal x 20°

  • 308 Winchester
  • Wildcat Cartridges necked down from the 308 Winchester

30 Cal x 30°

  • 300 SAUM
  • 300 PRC
  • 300 RUM

300 Norma Mag x 20.5°

  • 300 Norma Mag 

338 Lapua 20° 23 Minutes

  • 338 Lapua Magnum
  • Wildcat Cartridges necked down from the 338 Lapua Magnum

338 Cal x 40°

  • 338 Lapua Magnum Ackley Improved
  • 338 Norma Ackley Improved
  • 300 Norma Ackley Improved

Bullet Inserts for your Modular Headspace Comparator

Why are you measuring a single point on the bullets ogive like all other bullet comparators do? 

Our unique bullet comparator uses a 1.5 degree "lead angle" to contact your bullet's ogive in the exact same location as your barrel does, giving you the most accurate and useful measurements. 

For example, our 6.5mm Bullet Insert starts at a .266" diameter and angles down at 1.5 degrees to .256" diameter, exactly like a 6.5mm chambered barrel would. 

Manufactured from 17-4 Stainless Steel, our bullet inserts for the Modular Headspace Comparator are the most accurate way to measure your bullets and loaded ammunition for consistency.