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Head Space Gauges


Jaa

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Please will you state the range of sizes of these gauges.

 

Thank you.

 

JC

 

Engineered by Barry Neson, we all know how good he is.

1. Size .0395

2. "" .0405

3. "" .0415

4. "" .0425

5. "" .0435

6 "" .0445

7. "" .0455

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The head space is the distance from the face of the bolt to the chamber, if it's too large when you close the bolt on the case it will leave room to move when fired, this can have all sorts of issues with consistant accuracy.

 

thats the simple 'im only a sparky" version :blush:

 

I'm sure someone can give you far more details if you wish :rolleyes:

 

Alan

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Bill Calfee, one of the USA's leading Benchrest gunsmiths sets headspace between 42 thou and 44 thou.

 

If the headspace is too great it can cause inconsistent ignition, leading to loss of accuracy. By inconsistent ignition I am not referring to misfires.

 

As you know, the priming compound in the rim of the case ignites when struck by the firing pin.

 

If 1 cartridge is up against the breech face when the pin strikes, the resultant ignition will be different to a case which is up against the face of the bolt, and the firing pin pushes the case forward 2 or 3 thou before coming to a stop at the breech face, and THEN igniting. It is this inconsitent ignition which causes loss of accuracy.

 

What can you do about it?

 

Well, later model Anschutz (from the later 16 series with swept back bolt, to 18, 19 &20 series) can have a thin shim or shims fitted. These shims are available from guess who, that's right, Barry Nesom. (50p?)

 

Earlier 16 and 14 models have a plunger on the bolt handle which mates with a notch in the bolt body, and this chews the shims up in no time.

 

I believe the 20 series would have the headspace set by moving the barel in the action, which of course is clamped, not pinned.

 

It is also possible to get a new bolt handle from Anschutz (which must be sent to an RFD, as it is effectively classed as a firearm). I did this with Claire's 1607 in 2002, and it was sent to Ian Gibb who stoned it to the correct headspace.

 

Another method which I have observed in the Anschutz tent at Bisley, is to take the bolt apart and using a small hammer, tap the bolt around it's circumference at the point where the bolt handle butts up against it. This might be ok for an Anschutz technician, but I wouldn't recommend it for the rest of us!

 

Not sure about Walthers or other makes.

 

Hope this helps.

 

Walter

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