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Old 12-14-2009, 05:03 PM
Ericc Ericc is offline
 
Join Date: Oct 2009
Posts: 2,489
Default Headspacing (How to).

With all the requests for information on headspacing, I figured it was time to get a post up in the new forums.


Step 1. Clean the rifle chamber leaving no cosmoline or other material that would effect the measurements. If you have a chamber brush, use it. Remove any other grease, oil, and cosmoline from the action, including the locking lugs on the bolt and receiver.

Step 2. Strip the bolt. [Instructions]. Clean the bolt face at this time.

Step 3. Strip the action of the operational parts. [Instructions]

With the parts removed and your bolt stripped your setup should like the image below. (You do not need to remove the rear sight as shown below.)



Step 4. Insert the GO gauge gently into the chamber and install the stripped bolt into the receiver.

Step 5. Using finger pressure only, push the bolt closed. The bolt locking lug should look like the image below. The lug MUST be all the way down and contacting the receiver to pass the GO test.

[GO Gauge]



Step 6. Remove the GO gauge and install the NO-GO gauge. Using finger pressure only, push the bolt closed. The bolt locking lug should look like the image below. The lug MAY be all the way down and contacting the receiver. This does not yet indicate a rifle with excessive headspace. On a NEW barrel the locking lugs will look as shown below. As headspace increases the locking lug will move down toward the receiver.

[NO-GO Gauge]


Step 7. Remove the NO-GO gauge and install the Field gauge. Using finger pressure only, push the bolt closed. The bolt locking lug should look like the image below. The lug MUST NOT be all the way down and contacting the receiver. If the lug touches the receiver the rifle has excessive headspace. On a NEW barrel the locking lugs will look as shown below. As headspace increases the locking lug will move down toward the receiver.

[FIELD Gauge]


Step 8. Inspect your parts for wear and Re-assemble and lubricate appropriately.

Results:

[My Bolt wont close on a GO gauge!]

1. Did you remember to strip your bolt? Did you verify your chamber is clean and free of obstructions? Did you use the correct gauge?

2. Is your barrel new and not yet finish reamed? Did you accidentally swap bolts with another Garand?

[My Bolt closed on a NO-GO gauge!]

1. The NO-GO gauge is an intermediate gauge and by itself does not indicate excessive headspace. The results of the Field test will let you know if you have an issue.

[My Bolt closed on a FIELD gauge!]

1. Is the bolt locking lug actually touching the receiver? See image of the GO gauge test to see what fully locked looks like.

2. If the bolt lug is fully closed then your barrel/bolt combination has reached the end of its service life (In terms of head space). There are options available besides changing the barrel. I wont cover those here so ask on the forum.

Hopefully this will be useful to someone. Please let me know if I messed up something so it can be corrected.

Eric




Last edited by Ericc; 06-01-2015 at 04:27 PM. Reason: Updated Images
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Tags
field, gauge, headspacing, no-go

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