Checking Headspace in a bolt action

ThePunisher

ThePunisher

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My friend has a headspace guage set for .303 Lee Enfields. If I want to test a N04Mk1 with this guage, I remove the mag...and what else? Do I need to remove the extractor from the bolt as well? Some websites say you should, others say it doesn't matter. Can anyone clarify this for me? I know you push on the bolt very gently once the guage is in - and the moment you feel resistance, you stop, correct?
 
ThePunisher said:
My friend has a headspace guage set for .303 Lee Enfields. If I want to test a N04Mk1 with this guage,

I remove the mag...and what else?

Do I need to remove the extractor from the bolt as well? Some websites say you should, others say it doesn't matter. Can anyone clarify this for me?

I know you push on the bolt very gently once the guage is in - and the moment you feel resistance, you stop, correct?
Click to expand...

...Empty the chamber as well...

...Sometimes you need to remove the extractor, sometimes you don't...

...and yes...
 
"...remove the extractor..." CF Weapons Techs didn't when inspecting unit weapons. You really want the extractor there to get the guage out. Slip the guage under the extractor and gently close the bolt. It should close on the Go, but not on the No-Go. Definitely not on a Field. Use the Field if the bolt closes on a No-Go.
 
mysticplayer said:
If you didn't have the guages you can also use a fired case.

You just put tape on the back of the case until it will not close. Then the tape can be measured.

Quick and dirty.

Jerry
Click to expand...

Confirmed a head-space problem on my M1917 this way. (.030" worth of tape).
 
sunray said:
Bits of tape and empty cases tell you nothing about headspace.
Click to expand...


Bits of tape and a headspace gauge will though... a headspace gauge is made to an exact specification. Brass is made to varying inexact specifications smaller than a headspace gauge.
 
sunray said:
Bits of tape and empty cases tell you nothing about headspace.
Click to expand...

Please note the emphasis on rimmed cartridges to use the tape technique.

Your headspace is clearly defined by the rim.

As GT said, a go guage with a piece of tape now becomes a NO Go guage. Two or three pieces of tape becomes a field guage.

Ta da....

Jerry
 
A military field gauge is .074". If the bolt closes without resistance on a gauge/case plus tape/wad of frozen shzt, whatever, this thick, the rifle is too loose. Military Go gauge is .064". Civilian No Go is .068". If the bolt closes on ammunition, don't worry about the Go situation. Insufficient rim space is not a situation likely encountered, unless a new barrel is being fitted.
If you are not using gauges, you will need a way of making accurate measurements.
 
mysticplayer said:
If you didn't have the guages you can also use a fired case.

You just put tape on the back of the case until it will not close. Then the tape can be measured.

Quick and dirty.

Jerry
Click to expand...

That works, but always seems to offend someone.

Rather than layers of 3M masking tape .005" or some other brand that is .0045", I have been using store bought shim stock .0015".

I put it behind a Go gauge.

Lately I have been trying to headspace rifles with .001" over min headspace.

I try to adjust sizing dies for .001" of set back.

Then I neck size most of the time.


And before you get exited about a rifle that does not meet headspace, look at the tolerance built up with the SAAMI tolerances on 303 chambers and rims. If it gets any worse, the firing pin won't touch:)
 
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OK, my buddy only could find the field guage (it says .70 - I thought field for the .303 was .74?). I took the extractor out, as I was having trouble trying to get the guage in with it in place. I guess I was expecting something more dramatic or noticeable - I gently pushed the bolt until I felt resistance, and sumofabitsh, I was able to push the bolt handle down:eek:! Tried the guage on the other LE, same thing:eek:! What are the chances I thought! Then, I realised, the bolt handles were not all the way down...sooooo, I guess in my mind, I thought the bolt wouldn't even be able to move far enough ahead to lock down on a field guage. In reality, the bolt will start to lock, but stop before the bolt handle is completely locked down.

Am I correct in my understanding here?
 
Yes. If you study the locking surfaces, you will note that they are cut on a helix - an incline. The bolthead continues to cam foreward as the bolt rotates to lock. Military No Go is .074. Commercial .070. Rejecting an .070 gauge is better than rejecting a .074.
Use a light touch with gauges. If you gently feel resistance, that's it. Never use force.
 
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