SAC Modular Comparator Inserts – Headspace

Modular Headspace Comparator Inserts

Introducing the Modular Headspace Comparator Insert for Precision Measurement

The Modular Headspace Comparator Insert offers unparalleled accuracy for cartridge headspace and bullet measurements. This innovative insert works seamlessly with the Modular Headspace Comparator Body, which must be purchased separately, to deliver a highly adaptable tool for precise measurements. Designed with the user in mind, this modular insert simplifies the process of measuring headspace with exceptional accuracy.

Why Choose the Modular Headspace Comparator Insert?

Short Action Customs has reimagined its original headspace comparator, made from 6061 aluminum, to create a superior Modular Headspace Comparator. This updated version supports cartridges up to 338 Lapua Magnum, providing greater versatility and ease of use. Each bullet and headspace insert is precision machined from 17-4 Stainless Steel, ensuring maximum durability and corrosion resistance.

Compatibility and Usage

Our inserts are designed to measure relative headspace accurately. For those needing headspace measurements based on reamer prints, we recommend our Datum Gauges. If you’re uncertain about which insert to choose, we encourage you to verify your shoulder angle or datum size through the SAAMI Cartridge and Chamber Drawings.

Precision-Engineered for Reliability

The Modular Headspace Comparator ships with your choice of headspace comparator insert, selected conveniently from the dropdown menu. These inserts are crafted with precision, bringing you the highest quality in headspace and bullet measurement tools. Whether you are a professional or an enthusiast, the Modular Headspace Comparator Insert offers dependable accuracy for every measurement task.

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.

204 Ruger

•  204 Ruger

223 Rem

• 223 Remington and 5.56mm NATO

• 222 Remington

• Wildcat Cartridges necked down from the 223 Remington

22 Cal x 28°

• 22-250 Remington

• Wildcat Cartridges necked down from the 22-250 Remington

22 Cal x 30°

•  22 Creedmoor
• 224 Valkyrie
• 22 ARC
• 22 PPC

22 Cal x 35°

• 22 GT (6GT necked down to 22 caliber)
• FN 5.7x28mm

22 Cal x 40°

• 22 Dasher (Non-Alpha Chamber)
• 22 BRA
• 22-250 Ackley Improved

• 223 Ackley Improved

22 Alpha Dasher

• .22 Cal Dasher with an Alpha Legacy Reamed Chamber

6mm x 20°

• 243 Winchester

• Wildcat Cartridges necked down from the 243 Winchester

6mm x 26°

• 6mm Remington

6mm x 30°

• 6mm Creedmoor

• 6 x 47 Lapua

• 6BR

• 6BRX

• 6mm Super LR

• 6 ARC
• 6 PRC
• 6 XC
• 6 PPC

6mm x 35°

• 6GT

• 6mm x 284 Winchester

6mm x 40° 273” Neck Diameter, .060” Neck Shoulder Radius

• 6mm Dasher

• 6BRA (6mm BR Ackley Improved)

• 243 Ackley Improved

• Any 6mm Cartridge with 40° Shoulder and a fired neck diameter smaller than .273”

6mm x 40° .275” Neck Diameter, .060” Neck Shoulder Radius

• 6mm Dasher

• 6BRA (6mm BR Ackley Improved)

• 243 Ackley Improved

• Any 6mm Cartridge with 40° Shoulder and a fired neck diameter smaller than .275”

6mm x 40° 279″ Neck Diameter

• 6mm Ackley Improved cartridges with a fired neck diameter over .275″

6mm Alpha Dasher

• 6mm Dasher  with an Alpha Legacy Reamed Chamber

25 Cal x 30°

• 25 Creedmoor

• 25 x 47 Lapua

• 25 PRC

• 25 SAUM

• 25 SST

25 Cal x 35°

• 25 GT
• 25 x 284 Winchester

25-06 Remington

• 25-06 Remington

6.5mm x 20°

• 260 Remington

6.5mm x 25°

• 264 Winchester Magnum

6.5mm x 30°

• 6.5 Creedmoor

• 6.5 x 47 Lapua

• 6.5 PRC

• 6.5 SAUM

• 6.5 Grendel

6.5mm x 35°

• 6.5 Winchester Short Magnum

• 6.5 x 284 Winchester

• 26 Nosler

6.5mm x 40°

• 260 Ackley Improved

• 6.5mm Wildcat cartridges with a 40 degree shoulder

6.5-06 Springfield

• 6.5-06 Springfield

6.5mm x 55mm Swedish

• 6.5mm x 55mm Swedish

270 Winchester

• 270 Winchester

27 Cal x 30°

• 277 Sig Fury

• 6.8x51mm

27 Cal x 35°

• 6.8 Western

• 270 WSM

280 Remington

• 280 Remington

7mm x 20°

• 7mm-08

7mm x 25°

• 7mm Remington Magnum
• 7mm STW

7mm x 30°

• 7mm SAUM

• 7mm Creedmoor

• 7mm LRM

• 7mm PRC
• 6.5mm PRCW
• 7mm SPRC

7mm x 35°

• 28 Nosler

• 284 Winchester

• 7mm WSM

• 7mm/300 WSM

• 284 Shehane

7mm x 40°

• 7mm-08 Ackley Improved

• 280 Ackley Improved

• 7mm Wildcat cartridges with a 40 degree shoulder
• 7 TCU

.30 Cal x 20°

• 308 Winchester

• Wildcat Cartridges necked down from the 308 Winchester

.30 Cal x 30°

• 300 Remington Ultra Mag

• 300 SAUM

• 300 PRC

• 30 BR

.30 Cal x 35°

• 300 Winchester Short Magnum

.30 Cal x 40°

• 300 Norma Magnum Ackley Improved

• .30 Caliber Wildcat cartridges with a 40 degree shoulder

300 Blackout

• 300 AAC Blackout

30-06 Springfield

• 30-06 Springfield

300 Winchester Magnum

• 300 Winchester Magnum

300 Norma Magnum

• 300 Norma Magnum

300 Norma Magnum Improved 33°

• 300 Norma Magnum Improved 33°

338 Cal x 20°

• 338 Federal

338 Cal x 25°

• 338 Winchester Magnum

338 Cal x 30°

• 8.6 Blackout

• 338 RCM

338 Cal x 35°

• 33 Nosler

338 Cal x 40°

• 338 Lapua Magnum Ackley Improved

• 338 Norma Ackley Improved

• 300 Norma Ackley Improved

338 Lapua Magnum

• 338 Lapua Magnum

• Wildcat Cartridges necked down from the 338 Lapua Magnum

338 Norma Magnum

• 338 Norma Magnum

• Wildcat Cartridges necked down from the 338 Norma Magnum

33XC

• 33XC

37XC

• 37XC

375 Cheytac

• 375 Cheytac

375 Enabler

• 375 Enabler

If measuring for headspace off of a reamer print please select an insert from the below Datum gauge list

Datum A .330″

• 17 Remington
• 204 Ruger
• 220 Swift
• 221 Remington Fireball
• 222 Remington
• 222 Remington Magnum
• 223 Remington

Datum B .350″

Datum C .375″

• 6mm Remington
• 25-06 Remington
• 257 Roberts
• 6.5 X 55mm Swedish
• 6.5 Creedmoor
• 6.5mm X 47 Lapua
• 270 Winchester
• 7 X 57mm Mauser
• 7mm Winchester Short Magnum
• 280 Remington
• 30-40 Krag
• 30-30 Winchester
• 30-06 Springfield
• 300 H & H Magnum
• 7.62 X 39mm, M43
• 32 Special

Datum D .400″

• 223 Winchester Super Short Magnum
• 243 Winchester
• 243 Winchester Super Short Magnum
• 260 Remington
• 270 Winchester Short Magnum
• 7mm-08 Remington
• 300 Savage
• 303 British
• 308 Winchester
• 35 Remington

Datum E .420

• 257 Weatherby
• 6.5mm-284
• 264 Winchester Magnum
• 7mm Remington Magnum
• 7mm Remington Ultra Magnum
• 7mm Remington Short Action Ultra Magnum
• 7mm Shooting Times Westerner
• 8mm Remington Magnum
• 8×57 Mauser
• 8x68mm
• 284 Winchester
• 300 Winchester Short Magnum
• 300 Weatherby Magnum
• 300 Remington Short Action Ultra Magnum
• 300 Winchester Magnum
• 300 Remington Ultra Magnum
• 7.62x54R
• 325 Winchester Short Magnum
• 338 Winchester Magnum
• 338 Remington Ultra Magnum
• 35 Whelen
• 9.32x62mm
• 375 H & H Magnum