I feel like it`s a dumb question, but are these not practically the same - I can use any of these three options to see if the bolt will close. Or is the snap cap very inaccurate and the live round too dangerous for this test. I can see the no-go being important - thanks
Difference between go gauge, cartridge and snap cap
- Thread starter Peteroliver1234
- Start date
What are you trying to test? And NO, these things are not the same.
A GO-gauge is a precision ground steel gauge to have a rim thickness of 0.043", SAAMI minimum headspace for .22LR.
A "Snap-Cap" is a dummy cartridge designed for dry fire exercise. Rim thickness is somewhere "within" SAAMI spec for cartridges so that it will chamber in any firearm.
Cartridge spec is 0.036"-0.043" for rim thickness, and varies widely between brands. Cheap ammo will see each cartridge having a different rim thickness, sometimes being above or below spec. You'll never know unless you measure them.
Without knowing what you're trying to achieve, I can't really give you any suggestions.
A GO-gauge is a precision ground steel gauge to have a rim thickness of 0.043", SAAMI minimum headspace for .22LR.
A "Snap-Cap" is a dummy cartridge designed for dry fire exercise. Rim thickness is somewhere "within" SAAMI spec for cartridges so that it will chamber in any firearm.
Cartridge spec is 0.036"-0.043" for rim thickness, and varies widely between brands. Cheap ammo will see each cartridge having a different rim thickness, sometimes being above or below spec. You'll never know unless you measure them.
Without knowing what you're trying to achieve, I can't really give you any suggestions.
thepolinator
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You want to use a no go gauge. The other two won't tell you if its safe
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You could have headspace below minimum, lets say 0.039". If you used Eley ammo, which typically has rim thickness of 0.038" the bolt will close on this round. If you used Lapua with typical rim thickness 0.041"-0.042" the bolt will not close on this round. You have to be able to measure your rim thickness to make any kind of useful determination and always pull the bullet and dump the powder when working with cartridges for testing. Pull bullets at your own risk, there is danger of setting them off if you are careless so I do not recommend trying this.
If the bolt close on GO, that is only one step of the test. Headspace is an unknown value greater than 0.043" if this test is passed. The bolt cannot close on a NO-GO gauge to pass the test, and now you have determined your headspace is somewhere "within spec" and safe to fire. Closing on NO-GO isn't necessarily an automatic fail, but indication that maximum is being approached and more careful measurement required. A Field gauge is the final one used and if the bolt closes on this then headspace exceeds maximum and the firearm must be taken out of service.
If the bolt close on GO, that is only one step of the test. Headspace is an unknown value greater than 0.043" if this test is passed. The bolt cannot close on a NO-GO gauge to pass the test, and now you have determined your headspace is somewhere "within spec" and safe to fire. Closing on NO-GO isn't necessarily an automatic fail, but indication that maximum is being approached and more careful measurement required. A Field gauge is the final one used and if the bolt closes on this then headspace exceeds maximum and the firearm must be taken out of service.
Not really... go and no go gauges are made to specific measurements...
Ammunition often is made smaller, occasionally larger. Ammunition is made to different tolerance for different reasons.
If you want to check rifles for head space problems you use head space gauges.
On a military surplus rifle a third gauge can be used - a field gauge... larger than a no go gauge.
If a bolt closes on a no go gauge, the next step is to try a field gauge. If it closes on a field gauge then it should be taken out of service and fixed.
As I understand it the gauges are used in the reverse of your concepts:
Step 1: Try a Field Gauge and if it closes you would remove the rifle for repair or destruction due to dangerous head space; if it does not close then go to step 2.
Step 2: Try a No Go Gauge and if it closes you would have an oversized head space; if it does not close then go to step 3.
Step 3. Try a Go Gauge and if it closes you would have a proper head space within specifications; if it does not close take it to a knowledgeable gunsmith on that firearm.
The gunsmith will know if the gauges are being used right, if there is extractor interference, it is a tight or match chamber, or too tight and is dangerous.
The issue with a shell or snap cap being in the chamber and the bolt closing is simple: the head space could be so excessive as to be lethal !!! I know because I have grampy's old Lee Enfield on the wall and a snap cap or round will let the bolt close no problem... but firing a live shell is almost certain to be explosive! The chamber is lopsided, believe it or not, and partially separating rounds during firing have sliced the chamber. There was no way to know until the gunsmith tried the Field Gauge and then a needle camera tipped bore scope!
Play it safe and be sure you know what you are shooting.
No. A snap cap will be too thin to substitute for a GO gauge. If you can measure rim thickness you might be able to do a GO check, dig through a box of bulk ammo until one reads 0.043" which is GO gauge size. Passing only the GO test is not good enough alone! You MUST check NO-GO and possibly Field, these are the more dangerous ones to be out of spec. It sounds like you should be taking this to a qualified gunsmith... unless you're willing to drop $100 on a gauge set.
That makes sense - I don't want to buy the whole set, just the no go (and possibly filed Gauge), and use a cartridge for the go test, to see if bolt will close. If the bolt will close on a cartridge, and not close on a no go gauge, would you feel save to fire it?
If it doesn't close on a no go gauge that is what it is supposed to do... so as far as headspace is concerned it would be safe.
Gauges are made for the cartridge the rifle is chambered for... so you will need a no go gauge for each different cartridge you want to check.
Have you considered a gunsmith may have these gauges...
Thanks, that does answer my question. I can't run to a gunsmith every time I want to check a milsurp, I have too many, more piratical to get a no go gauge. Thanks
