Go Gauge Question...

[ridgeway]

I plan on doing my first chamber job when I get my 6BR reamer in a few weeks. I ordered it when PTG had their Shot Show sale on them along with several 6mm bushings. I have several used 14 twist used barrels laying around that I plan on using to fit to an XP-100 that I have that is already in 6BR.

My question is, I have a Clymer 6BR Go Gauge and I wanted to see how it fit in the existing 6BR chamber. I removed the firing pin assembly from the bolt to test and the bolt does not come close to closing and I don't know why. The gun flat out shoots as it is. I measured the Go Gauge and a FIRED case that DOES chamber freely. The Go Gauge measures 1.5730" and the case runs 1.5735". The shoulder is longer in the fired case opposed to the Go Gauge. Now why won't the bolt close on the Go Gauge? The bump gauge is one that comes with a Harrell die. I measured several times keeping a close feel for consistent pressure on the calipers. The Go Gauge seems to slide into the chamber fine.

 

[shortgrass]

Did you remove the ejector? Did you hook the gauge under the extractor?

 

[ridgeway]

Did you remove the ejector? Did you hook the gauge under the extractor?

I did not. I will give that a try. The spring I have behind the plunger is very light though.

 

[ridgeway]

I removed the plunger and hooked the gauge under the extractor. Bolt still does not close...it starts to, but nowhere near closing. Seems like a few tenths is all is needed.

When I do the chamber...should I shoot for the same feel, or make it close under a tiny bit of resistance?

 

[DOGCAPPER]

It would seem to me the chamber is cut with a non-standard reamer. The go gauge is bumping the body side toward the shoulder. Once the case is fired in the chamber it is ok. Like any fire formed wildcat round. Reamer may have been sharpened one time too many.

 

[Erik Cortina]

Go gauges can vary in length. The go gauge used to chamber barrel may have been shorter.

If the same gauge was used, then the difference may have to do with the hardness of the brass vs the gauge. You can crush .001" fairly easy on brass, not as easy on hardened steel.

Make sure your new chamber closes on the go gauge.

 

[gunsandgunsmithing]

Erik is right...gauges do vary slightly. We often assume things like these to be perfect, and while the makers do a great job...there is no such thing as perfect, just lesser degrees of F'd up. Machinists know what I'm talking about, but if you think something is absolutely perfect, just keep adding another decimal point. A chamber set up for a light "feel" on a given go gauge is pretty definitive. Any difference between gauges will be apparent. Much the same as trying to put a 1.000000" rod into a 1.000000" hole. It does not fit.--Mike

 

[shortgrass]

Erik is right...gauges do vary slightly. We often assume things like these to be perfect, and while the makers do a great job...there is no such thing as perfect, just lesser degrees of F'd up. Machinists know what I'm talking about, but if you think something is absolutely perfect, just keep adding another decimal point. A chamber set up for a light "feel" on a given go gauge is pretty definitive. Any difference between gauges will be apparent. Much the same as trying to put a 1.000000" rod into a 1.000000" hole. It does not fit.--Mike

+1 to the above quote. It is also recommended that reamers and gauges be aquired from the same manufactuer.

 

[ridgeway]

Thanks guys...after I removed the ejector plunger, the bolt handle partially went down. I'm guessing a few tenths is all it would need to drop freely. I kinda figured then that all the gauges do vary some.

 

[MDSpencer]

I agree with Erik, they do very!

 

[Rtheurer]

+ 1 to what Erik said. Found this same thingout this summer with a 308 Go gage I had and used on all my Palma Barrels... No one barrows ammo from me now since it wont fit there rifles... So maybe its not a bad thing????

Live and learn.

RT