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300 AAC Blackout Headspace Gauge Set GO and NO-GO

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$93.54

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300 AAC BLACKOUT: Use to check headspace of 300 AAC Blackout
RIMLESS CARTRIDGE HEADSPACE: The proper use of Headspace Gages is the most reliable way to test rifle chamber length. Headspace in a rimless cartridge is the distance between the bolt face and a datum line, determined by SAAMI, where the front of the cartridge rests on its shoulder when the bolt is closed.
NO-GO: Corresponds to the maximum headspace we recommend for gunsmiths’ chambering new bolt-action rifles. This is not a SAAMI-maximum measurement. If a rifle closes on a NO-GO gage, it may still be within SAAMI specifications, or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gage. The NO-GO gage is a valuable tool for gunsmiths’ reaming new chambers, in order to ensure tight and accurate headspace
GO: Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gage, the chamber will accept ammunition that is made to SAAMI maximum specifications. The GO gage is essential for checking a newly-reamed chamber in order to ensure a tight, accurate, and safe chamber that will accept SAAMI maximum ammo.
PRECISION MACHINED: Manufactured from top-quality, hardened steel and precision ground to ANSI and SAAMI tolerances. Headspace tolerance ground to a very exacting ±.00015. Each Headspace Gage thoroughly inspected with NIST-certified measurement tools to ensure the highest quality product.

Every gunsmith knows that proper use of a headspace gage is the most reliable way to test the length of a rifle chamber. “Headspace” is the distance between the face of the breech and the base of the cartridge when the action is closed, and excessive headspace can be dangerous as well as impair accuracy. For instance, unsupported brass fired in a rifle action with excessive headspace can rupture, allowing gas to blow rearward like rocket exhaust. Because your safety is on the line, Forster Headspace Gages are made with painstaking care and exacting manufacturing standards to ensure accurate testing of your rifle’s chamber. If a rifle closes on a GO gage, the rifle chamber will accept any ammunition that is made within SAAMI (industry standard) specifications. If a rifle closes on a NOGO gage, the rifle chamber might have excessive headspace. Most gunsmiths chamber a rifle’s headspace between the GO and NOGO dimensions. If a rifle closes on a FIELD gage, the rifle chamber is dangerously close to or already over the SAAMI specified maximum chamber size.

Chris Coblentz

2025-08-30 10:18:27

works as described.

Spliner

2025-08-24 10:05:20

The gauges seem to work fine for my new rifle barrel. The action closes on the Go gauge and doesn't on the No Go gauge. That's pretty much all they are good for, and seem to be in spec.

Patrick Crow

2025-07-26 16:07:26

Purchased this set to do as the name says. Started with the No-Go gauge bolt didnâ€™t close as expected. Moved on to the Go gauge, bolt still would not close. Tried with a dummy round, bolt would close just fine. Got my caliper out and checked the specs of the gauges. Both of them were out of spec from what was printed on the side of the gauge by a significant amount. You can shoot your shot on them working for you but just know you run the chance of having to send them back.

Troy Ringle

2025-06-26 10:28:24

Nice set at a good price

DieselDuc

2025-06-25 09:57:56

I used these to check my head spacing(as the name suggests) on my build and they work as they should, and Iâ€™ve had no issues after a few hundred rounds.

Michael Ladousier

2025-06-02 20:11:57

Forster products have never let me down!

Mike Bergquist

2025-01-24 12:04:55

Works as advertised.

Customer

2024-11-15 12:57:29

Great product.

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300 AAC Blackout Headspace Gauge Set GO and NO-GO