[Back in the USSR]

Guys I recently bought a m39 and I bought a set of okie headspace gauges. My rifle passed the go gauge but it didn't close on the no go or field. Is the headspace always this tight on these rifles. I was always told that most military rifles would close on the field gauge.

 

[jbsx]

Why would you want it to close on the no-go or field gauge? That would mean headspace is no good.

 

[tuco In Memoriam]

Sort of lost me as well as those sound like good things

 

[Back in the USSR]

It is a good thing. I was just curious because, I've heard a lot of military guns will close on the field gauge. I know the fin is no slouch, but I was curious if people find that their mosins close on field?

 

[jbsx]

I have yet to find a mosin that will close on the field gauge, let alone the no-go gauge. If it does close on a no-go, you use the field gauge since it is slightly larger than the no-go. (More allowance for military rifles)

 

[Ed Novak]

I have yet to find a mosin that will close on the field gauge, let alone the no-go gauge. If it does close on a no-go, you use the field gauge since it is slightly larger than the no-go. (More allowance for military rifles)

It is my understanding (with respect to rimmed cartridges) that failure to pass the 'no go' gauge indicates a headspace that is not going to allow the bolt to come near to closing on a milspec cartridge. Failure to pass the 'go' gauge indicates too short headspace. Failure of the bolt to close on a 'field (field reject)' gauge indicates that headspace is not excessive. In the .303Br (same for the 7.62X54R, I think), the 'no go' gauge is 0.064", the 'go' gauge is 0.070" and the 'field' gauge is 0.074" in rim thickness.

 

[jbsx]

failure to pass the no-go means the bolt closes on it. If it fails the no-go, it will close on any cartridge made for that rifle but might have excessive headspace. In order of thickness, the go is the thinist, followed by the no-go, than theh field gauge. To pass the go, the bolt must close on it. The pass the no-go, the bolt must not close on it (with gentle pressure - one finger). If it fails to pass the no-go, the field gauge gives a larger allowance meaning there is some wear but if it passes the field gauge, it is still acceptable.
Failure to pass a go gauge will cause a bolt that won't close on a round.

 

[Ed Novak]

failure to pass the no-go means the bolt closes on it. If it fails the no-go, it will close on any cartridge made for that rifle but might have excessive headspace. In order of thickness, the go is the thinist, followed by the no-go, than theh field gauge. To pass the go, the bolt must close on it. The pass the no-go, the bolt must not close on it (with gentle pressure - one finger). If it fails to pass the no-go, the field gauge gives a larger allowance meaning there is some wear but if it passes the field gauge, it is still acceptable.
Failure to pass a go gauge will cause a bolt that won't close on a round.

I have always hated the 'names' assigned to the gauges! Your explanation does make a clearer picture for me. Thanks.

 

[jbsx]

Yea, very confusing. I like the okie gauges. They are marked with a single dot on the go, 2 dots on the no-go, and 3 on the field. Close on 1 dot. Don't close on 2 dots and 3 dots. If it does close on 2 dots you still have the 3 dot gauge to not close on. Plus no extractor removal.
I don't remember the sizes of the gauges (I think you're right on the thicknesses you posted earlier) but the rim of a 7.62x54 is .064 so the go gauge should be that thickness and they get thicker from there.

 

[bdgfate]

I was just curious because, I've heard a lot of military guns will close on the field gauge.

I think you're confused. Many milsurps will fail the "no go" because of the loose tolerances built in to their design to keep them running in battlefield conditions. That's why the only gauge you need to use is a field. Any that fail the field gauge should not be fired.

 

[Ed Novak]

I think you're confused. Many milsurps will fail the "no go" because of the loose tolerances built in to their design to keep them running in battlefield conditions. That's why the only gauge you need to use is a field. Any that fail the field gauge should not be fired.

Years ago, back in the days when I bought milsurp rifles in what I considered VG condition and just shot them. Then days "HEADSPACE" raised its ugly head and I bought a 'no-go' gauge from Brownells, not understanding that the gauge was a SAAMI spec and nearly all of my LEs flunked! Then an Australian told me to buy a .074" gauge, not to worry about names; I did and ALL of my LEs (and my MNs and M39s) are in fine fettle. I tried to give that SAAMI gauge away several times.. Yes, the Okie gauge is magnificent, I put my Clymer gauge away in oiled-paper.

 

[Shermysan]

I only have a field gauge. Out of more Mosins than I can count, I found only one Mosin a, Remington 1891 that failed a field guage. Shermysan