Go gauge lessons learned

[CaptJim]

This may be old news but I thought it might help someone.

Go gauge 'A' 1.569". Go gauge 'B' 1.574.
I had a 6mm / 22-250 chambered a while back. It is a Remage, once I received it I headspace it with a 22-250 go gauge so the bolt would close smoothly on the gauge with firing pin and ejector removed. The bolt would just about fall by itself.
I then loaded up a few rounds using Hornady brass sized with a Redding FL bushing die. I set the die to touch the shell holder and just a smidgen of cam-over on my Rockchucker.
I tried a couple in the gun to make sure they chambered, and they were a bit snug, so I screwed the sizer in a tiny bit further and the chambering was still snug but better. I wanted to see if the fired brass would be better.
I shot the rifle during the break-in and that went fine, I then made one trip to the range - rounds still chambering snug. I was resizing the brass as much as I could without altering the shell holder.

Cutting to the chase. I decided to re-check my headspace.

Inserting the go gauge again with the bolt stripped the bolt closed as before, with the slightest resistance.
I loosened the barrel nut and re-adjusted the headspace sticking small pieces of shim stock to the back of the go gauge using grease to hold them in place in increments to see where the brass would chamber better. At each step I chambered a brass. All measurements were made using Whidden shoulder gauge and Mitutoyo caliper.

1: Go gauge 1.569" base to shoulder datum. Chamber stiff or not at all.
2: Go +.003 almost same as #1
3: Go + .004 better but still slight resistance.
4: Go + .005 nice smooth close.
5: Go + .006 bolt did not close, only moved a few degrees.
So my headspace was actually 1.574" base to shoulder datum. The brass was an average of 1.572 plus or minus.
I wondered about this situation so I decided to check other go gauge dimensions in case mine was short for some reason.
Upon checking a different manufacturer ( lengths are not always listed for these ) I find their Go is 1.574" which is just where my brass started to chamber correctly.
I had no Idea that there would be that much variance in these tools. Then again my gauge might have missed the QC check.
I think the lesson here is that even things that are usually very consistent can sometimes bite if we're not careful.
CJ

 

[GLShooter]

I prefer HS gouges done by the reamer maker. I know who that is on most of my barrels.

 

[CaptJim]

I prefer HS gouges done by the reamer maker. I know who that is on most of my barrels.

I hear you! Never thought of that, but PTG made my reamer. It makes good sense to get one from them!!
Thanks

 

[William Vogel]

Just looking at the SAAMI minimum spec for headspace on a 22-250 they say 1.5749. I’m not an expert on this but I measure my brass and compare it to the spec. My bolt guns are all Remington 700 variants. I have no way to adjust headspace but I haven’t run into a short chamber.

 

[Coyotefurharvester]

So adding 0.005 to hs go gage length made it chamber correctly, but just the go gage was hard to chamber?

 

[762plinker]

simple question
is the widden shoulder gauge actully cut at the head space reference dia ??

 

[CaptJim]

So adding 0.005 to hs go gage length made it chamber correctly, but just the go gage was hard to chamber?

No: this from the first paragraph.
I had a 6mm / 22-250 chambered a while back. It is a Remage, once I received it I headspace it with a 22-250 go gauge so the bolt would close smoothly on the gauge with firing pin and ejector removed. The bolt would just about fall by itself.

It was the brass that was tight. By using the short gauge above (1.569"), the average sized brass was too long. The gauge I looked up was 1.574, that would have been correct.
CJ

 

[CaptJim]

simple question
is the widden shoulder gauge actully cut at the head space reference dia ??

I would think so, but I don't know. That's a good question. What I do know is it took
the go gauge (1.569")+.005" added to the gauge to allow brass to chamber smoothly. It was Ironic that that 1.574" was the length of the other manuf's gauge.

 

[Lone Hunter]

Look straight down this page and you will see a light blue banner that says similar threads. A lot of times there are some threads there to help ,sometimes not. Anyway, here is a thread talking about incorrect HS gauges. I have been fortunate on mine in that they all were right. ( Knock on Wood )

Undersized No-Go gauge?

I searched, but didn't find any threads discussing No-Go gauges that are smaller than virgin brass. So, here goes. NUTSHELL: 250 Savage cartridge. Stevens 200 (Sav. 110?) small shank. My no-go gauge is smaller than my virgin brass. While setting headspace, the bolt will lock up on brass before...

forum.accurateshooter.com

 

[17cal Fan]

If you were tightening the barrel nut after setting headspace you could lose a couple thou there. Been there cussed that.

 

[CaptJim]

Look straight down this page and you will see a light blue banner that says similar threads. A lot of times there are some threads there to help ,sometimes not. Anyway, here is a thread talking about incorrect HS gauges. I have been fortunate on mine in that they all were right. ( Knock on Wood )

Undersized No-Go gauge?

I searched, but didn't find any threads discussing No-Go gauges that are smaller than virgin brass. So, here goes. NUTSHELL: 250 Savage cartridge. Stevens 200 (Sav. 110?) small shank. My no-go gauge is smaller than my virgin brass. While setting headspace, the bolt will lock up on brass before...

forum.accurateshooter.com

Yep, I'll do the search next time. That guy had the exact same problem.

 

[SKWERLZ]

I always check my gauges, brass and reamer print on a new combination before proceeding especially on the first go around.

 

[JSH]

IMHO, when you go with a wildcat, headspace is what you make of it, just a number.

 

[Old Navy]

For the OP: How did you set the headspace? Holding the barrel, holding the action, torque wrench or Millwright hammer wrench?

 

[JimSC]

I just buy a GO and a NO GO gage from the same manufacturer and use them as directed and never have to worry or second guess myself. I set my sizing die to size the shoulder to the same shoulder datum as the go gage. Never had a neck split or case failure in 15 years of using this method. Ammo can be swapped between rifles and when switching barrels can be used as is. I have 92 pieces of .308 Lapua brass that were bought in 2009 that have over 20 reloadings, the majority of which were some fairly hot Palma loads. Been shot in 4 different barrels with zero issues. Some 260 Remington brass that I lost count on both in the number of reloadings and the number of barrels it has been used in. The savings in brass alone covered the cost of the NO GO gage many times over.

Just buy the proper tools and life is simple, a NO Go gage is less than 50 Bucks and never wears out.

Just my 2 cents worth
Jim

 

[SKWERLZ]

I just buy a GO and a NO GO gage from the same manufacturer and use them as directed and never have to worry or second guess myself. I set my sizing die to size the shoulder to the same shoulder datum as the go gage. Never had a neck split or case failure in 15 years of using this method. Ammo can be swapped between rifles and when switching barrels can be used as is. I have 92 pieces of .308 Lapua brass that were bought in 2009 that have over 20 reloadings, the majority of which were some fairly hot Palma loads. Been shot in 4 different barrels with zero issues. Some 260 Remington brass that I lost count on both in the number of reloadings and the number of barrels it has been used in. The savings in brass alone covered the cost of the NO GO gage many times over.

Just buy the proper tools and life is simple, a NO Go gage is less than 50 Bucks and never wears out.

Just my 2 cents worth
Jim

I have seen incorrect go gauges, you still need to check them.
I personally use just a go gauge and clear package tape to increase the datum length as needed
I make my own precisely bored or reamed datum gauges to check the gauge, tape stack and cases.

 

[JimSC]

I have seen incorrect go gauges, you still need to check them.
I personally use just a go gauge and clear package tape to increase the datum length as needed
I make my own precisely bored or reamed datum gauges to check the gauge, tape stack and cases.

define incorrect. Notice I stated using a Go and NO GO gage from the same manufacturer. You cannot mix say a Forster with a Manson etc, it is pretty likely their measurements will be slightly different. Notice on SAAMI spec drawings that there is a minimum and a maximum shoulder measurement datum. The Forsters could be made to the minimum spec or somewhere in between. They will be in the correct relation to each other however and the GO gage should no be shorter than the min and the NO Gage should not exceed the max. I got that piece of advice from the best benchrest smith in the state back when I was learning how to rebarrel using drop-in barrels on Savages. As long as you use gages from the same manufacturer they will safely chamber and fire both production ammo and your handloads.

So do you make you gages to SAAMI min , max or somwhere in between the two numbers? Either would be correct as long as your Go and No GO are in relation to each other

 

[SKWERLZ]

Incorrect length from base to datum
Interestingly all of the ones that were off were from a well known supplier here on the west coast.

 

[JimSC]

Incorrect length from base to datum
Interestingly all of the ones that were off were from a well known supplier here on the west coast.

Was the Go gage shorter than the SAAMI minimum or was the NO GO longer than SAAMI maximum ? Or was the measurement somewhere in between? I have Forsters and Mansons and it is too late and I am too tired to go do measurements right now but I can almost guarantee that none of them will measure exactly to SAAMI min/max specs and if I switch between my Sinclair and my Hornady comparators the measurements could change because the comparators may be bored plus or minus a couple of ten thousandths different. None however would be dangerous if used correctly

On that, I am going to go to bed rather than get into a hair-splitting contest

 

[CaptJim]

For the OP: How did you set the headspace? Holding the barrel, holding the action, torque wrench or Millwright hammer wrench?

Holding barrel. No torque wrench, barrel nut is hex so used open end, probably about 30 ft/lb, then ck bolt feel.