GO gauge

[Brownie]

Thought I would ask here? Wondering if anyone has a spare .308 Win. GO gauge they would like to part with??

 

[sloughfoot]

A "go" gauge is the same as a factory round. I will sell you one factory .308 round if you really think you need it.

 

[CountryBoy19]

A "go" gauge is the same as a factory round. I will sell you one factory .308 round if you really think you need it.

Actually that isn't necessarily true. A go guage is a precisely machined gauge to determine if chamber dimensions (mostly headspace) are proper. Just because a factory round will chamber doesn't mean the head-space is proper.

I may have a go-gauge that I would loan out but it will be quite a while before I can get to it and get it sent to you.

 

[Brownie]

Country boy...Thank you for the offer I may take you up on it if I still need it by the time you locatevit. Much appreciated.


And Slough foot. I happen to be a toolmaker by trade. And while you may be able to use a "factory round" they are very much NOT THE SAME! I could machine one harden it grind it etc. Just not worth the time nor trouble when I can buy one for 30$.

 

[engineerpower]

Actually that isn't necessarily true. A go guage is a precisely machined gauge to determine if chamber dimensions (mostly headspace) are proper. Just because a factory round will chamber doesn't mean the head-space is proper.

Forgive me if I'm mistaken, but I believe the purpose of a "GO" gauge is to establish the presence of a minimum headspacing, the goal being to see that the bolt will close and lock up on a properly sized round. If the bolt closes and locks up on a properly sized round, are we not in a "GO" state? The "NO-GO" is to identify instances where headspacing is excessive and tells you "Don't shoot!"

All the dimensional work on the gauge is to prevent false negatives when trying the "GO" or "NO-GO" gauges. If a false negative in "GO" simply means your bolt isn't closing on a kosher round, the consequences are minimal and the user will most likely try a new round and find it better.

 

[sloughfoot]

Lots of people seem to worry way too much about headspace, especially if they are shooting new ammo or if they are reloaders.

Wlidcat cartridges frequently have wildly excessive headspace. At least for the first firing.

Even factory chambers have a range of allowable headspace. None of which are a dager to anything. When reloading, for a given rifle, the case is only resized to allow smooth chambering. No more.

 

[CountryBoy19]

Forgive me if I'm mistaken, but I believe the purpose of a "GO" gauge is to establish the presence of a minimum headspacing, the goal being to see that the bolt will close and lock up on a properly sized round. If the bolt closes and locks up on a properly sized round, are we not in a "GO" state? The "NO-GO" is to identify instances where headspacing is excessive and tells you "Don't shoot!"

All the dimensional work on the gauge is to prevent false negatives when trying the "GO" or "NO-GO" gauges. If a false negative in "GO" simply means your bolt isn't closing on a kosher round, the consequences are minimal and the user will most likely try a new round and find it better.

You are somewhat on the right track but not entirely correct. There are 2 main reason that I can think of that eliminate a factory cartridge as a reliable "GO Gauge". #1 Factory rounds are sized SMALLER THAN chamber dimension to ensure they feed easily. Utilizing one as a go-gauge, while not catastrophic, may tell you that your chamber is good, when in-fact it is too short. A GO gauge is made precisely to just fit into a chamber that is to minimum head-space. Is it a problem if you get a "go" indication when your chamber is too short? It is when you switch ammo and all of the sudden you can't get it to feed or can't close the bolt... #2 Manufacturing isn't perfect. Even if cartridges were the exact size of the chamber, they couldn't be manufactured that precisely every time. This is why cartridges are made a bit under-sized. There is an acceptable spread of "sizes" coming off the assembly lines. The large to small window of acceptable sizes is called manufacturing tolerance and is likely proprietary to each manufacturer and even different within different product lines of the same manufacturer. So we have all these cartridges out there by different manufacturers and different product lines may be tighter toleranced than others, which one is the "best" for a "Go gauge"? Do you know? I don't either, that is why I will continue to use real gauges. There is no equivalent substitute for a proper gauge, only short-cuts.