Proper use of GO/NOGO gauges

[perry42]

What is the best way to properly use GO/NOGO gauges?

perry42

 

[Jammer Six]

Check the weapon's condition of readiness, chamber the Go gauge. The weapon should lock closed. Chamber the No-Go gauge. The chamber should not lock closed.

If it fails either test, take it to a gunsmith or pass on buying it.

 

[Keith Glasscock]

Ummm, A little more explanation is in order.

Here is how I use them:

Obviously, rifle unloaded and pointed in a safe direction.

First, you have to ensure that nothing is going to bias the result of the test. For example, on a bolt action rifle, removal of the ejector and firing pin are recommended. Remember that we are "feeling" for the gauge not seeing if we can force it into the chamber.

Next, we ensure that the locking lugs clean and are lightly lubed. The chamber should be clean as well.

Finally, we insert the Go gauge and attempt to close the bolt. The bolt should close freely. Ideally, one would feel a very slight amount of contact between the gauge and bolt face while the bolt rotates into position. That is not always the case. I specify a touch more headspace for my rifles, so the bolt falls closed with no feel.

Remove the Go and insert the No-Go. With light pressure on the bolt handle, the bolt should not close. Realistically, it should jam up at the top of bolt rotation.

Finally, remove the gauges and reassemble the bolt (ejector, firing pin).

 

[fguffey]

Here is how I use them:

There are so many reloaders that post on the internet that respond when they hear trigger words; a trigger word sets them off into an automatic response. Meaning I can do anything with a no-go gage that I can do with a go-gage and then there is the field reject length gage.

F. Guffey

 

[DRNewcomb]

My understanding is that the proper use of GO and NO-GO gauges involves chamber reaming. For use when shopping it's good if the bolt does no close on a NO-GO gauge and you should not buy if it will close on a FIELD gauge. Of course, the class of rifle discussed here would never be so worn as to close on a FIELD gauge.

 

[perry42]

THANKS to all for the replies.

perry42

 

[M-61]

Was your question for a particular rifle you are assembling or just for general info?

 

[fguffey]

For use when shopping it's good if the bolt does no close on a NO-GO gauge and you should not buy if it will close on a FIELD gauge. Of course, the class of rifle discussed here would never be so worn as to close on a FIELD gauge.

I want to know the length of the chamber from the shoulder to the bolt face in thousandths. If I know the length of the chamber in thousandths I know how long the case should be from the shoulder to the case head.

F. Guffey

 

[DRNewcomb]

I want to know the length of the chamber from the shoulder to the bolt face in thousandths. If I know the length of the chamber in thousandths I know how long the case should be from the shoulder to the case head.

Let's face it, we're the 1/2 of 1% here. If Joe Collector is looking for an '03, 1917 or Garand, he may carry a FIELD gauge when appraising if the gun is safe to shoot. That's only if he's a very savvy shopper. Most don't bother.

 

[Rpbump]

I am assembling a 338 Edge in a Savage 110 LA reciever. Using a prefit barrel and want to be sure about head space. The rifle is just for satisfying my curiosity about long range (1400 to 2000yds). Less than 80 rounds have been run through this barrel. Upon removing the muzzle brake I could see that the barrel muzzle needed to be refaced/squared. The bore and chamber look great but due to the pressure this cartridge developes I want to be careful.


perry42

 

[M-61]

I am assembling a 338 Edge in a Savage 110 LA reciever. Using a prefit barrel and want to be sure about head space. The rifle is just for satisfying my curiosity about long range (1400 to 2000yds). Less than 80 rounds have been run through this barrel. Upon removing the muzzle brake I could see that the barrel muzzle needed to be refaced/squared. The bore and chamber look great but due to the pressure this cartridge developes I want to be careful.


perry42

Keith Glasscock's instructions above are quite complete. My only input concerns Savage. If it's not you first time ignore it, if not, briefly I would say:
Run the jam nut all the way on. Insert the go gauge. Close the bolt. Screw the barrel into the action until it stops. Run the jam nut down until it contacts the action. Replace go gauge with no/go. The bolt should as Keith said "...jam at the top of the bolt rotation". Remove gauge. A bit tricky but tighten the jam nut trying not to rotate barrel. If you have done this before you know that re-checking (both go & no/go) that the barrel did not move is mandatory. I use 35 ft.lbs on the nut, and have never had one come loose. Then I recheck again with both gauges. For me the nightmare starts with replacing the extractor ball in the bolt. (plastic bag and a box with plenty of extras.)

 

[fguffey]

A bit tricky but tighten the jam nut trying not to rotate barrel.

Two wrenches while using one hand secures the jam/lock nut and removes slack.

F. Guffey

 

[fguffey]

Less than 80 rounds have been run through this barrel. Upon removing the muzzle brake I could see that the barrel muzzle needed to be refaced/squared. The bore and chamber look great but due to the pressure this cartridge developes I want to be careful.

How can that happen? I have been told the cleaning rod wares out the muzzle and now you are saying it happens with less than 100 rounds. Again, I saw a picture that proved hot high pressure metal cutting gas escaping the muzzle cut the muzzle" I was told the cleaning rod did all that damage so I made a cleaning system for the barrel JIC; as in just in case the cleaning rod is the problem. Point; there is nothing I can do to prevent gas cutting of the muzzle by gas. And then there are tapered gages for measuring taper, most will measure the taper caused by the cleaning rod others assume the diameter of the barrel is perfect.


F. Guffey

 

[ireload2]

The barrel diameter is easy to check with a micrometer.
Don't you mean the land diameter?

How can that happen? I have been told the cleaning rod wares out the muzzle and now you are saying it happens with less than 100 rounds. Again, I saw a picture that proved hot high pressure metal cutting gas escaping the muzzle cut the muzzle" I was told the cleaning rod did all that damage so I made a cleaning system for the barrel JIC; as in just in case the cleaning rod is the problem. Point; there is nothing I can do to prevent gas cutting of the muzzle by gas. And then there are tapered gages for measuring taper, most will measure the taper caused by the cleaning rod others assume the diameter of the barrel is perfect.


F. Guffey

 

[danny]

My understanding is that the proper use of GO and NO-GO gauges involves chamber reaming. For use when shopping it's good if the bolt does no close on a NO-GO gauge and you should not buy if it will close on a FIELD gauge. Of course, the class of rifle discussed here would never be so worn as to close on a FIELD gauge.

I align with this posting most of all. "GO" and "FIELD" align most closely with SAAMI Minimum and Maximum.

Danny

 

[M-61]

The OP is assembling his OWN Savage.

 

[perry42]

It is my opinion that who ever installed the brake did a poor job on the internal parts you cannot see. Externally the fit of the brake to the barrel is flawless. My curiosity is what led me to looking at the "parts unseen". The flaws will be corrected by a gunsmith not by me.

perry42