Head spacing with only a FIELD gauge.

[tenOC]

I've read where people state they only use the FIELD gauge when checking head spacing. Is that really common?

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[jimb16]

Yes, particularly if you have a used firearm. In all likelyhood a used firearm does not have too short a chamber unless you have changed the barrel. So for a used firearm you really want to know that the headspace is within acceptable limits.

[tenOC]

I have one that closes easily on the NO-GO. But doesn't on the FIELD.

[painter777]

I have one that closes easily on the NO-GO. But doesn't on the FIELD.

From a Brownells how to:

On older military rifles:
An old military surplus rifle like a Mauser, Mosin Nagant, '03 Springfield, Enfield, Arisaka, and others may close on a NO-GO gauge. If it does, check it with a FIELD gauge. A FIELD gauge measures the absolute maximum allowable, safe headspace. If the bolt does not close on a FIELD gauge, and the gun is in good condition, it is generally safe to shoot.

To add:
However, the strength of these old guns can vary a lot depending on when and where they were manufactured. Headspace is not the only factor in deciding whether one of these guns - or any gun for that matter - is safe to shoot. When in doubt, take it to a qualified gunsmith to have it checked out.

Link:
https://www.brownells.com/guntech/he....htm?lid=17125

Best to have a real clean chamber, dry with no oil or solvents.

[tenOC]

I feel a lot better reading about the 1.302 value being the lowered bar.

[JackP]

Just know that the standard for the maximum head space has evolved over time. Early TM's specify 1.300". Later TM's specify 1.302". Modern commercial field gauges (Forster) are 1.299". So it makes a difference which "Field" gauge you use. I recommend the more conservative 1.299" gauge. If it barely closes on this gauge you may still be okay according to the TM's, but be careful.

[tenOC]

Ok. My Forster Field does measure that 1.299.
The No-Go is 1.297 and the Go is 1.291.

[USGI]

Ok. My Forster Field does measure that 1.299.
The No-Go is 1.297 and the Go is 1.291.

Ten, are they also stamped with those same numbers? I guess mine are older than I thought - without pulling them out, I remember them as 1.290, 1.296, and 1.302. - Bob

EDIT: Correction - My field gauge is stamped 1.299 - not 1.302.

[Sunray]

"...only use the FIELD gauge..." That doesn't actually check the headspace. It only tell you the thing is at less than max.
Yours closing on the No-Go but not the Field indicates it's safe to shoot, but is close to max.
"...My Forster Field does measure..." Headspace gauges do not 'measure' anything. They only tell you if the thing is within tolerance or not.
Graf's shows the Forster No-Go gauge to be 1.296". Not that it matters. They don't list the other 2 gauges.

[USGI]

"...My Forster Field does measure..." Headspace gauges do not 'measure' anything.

I believe he's saying he measured the gauge - that's why I asked if it was stamped. - Bob