Undersized No-Go gauge?

[marfish]

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 it will on the No-Go.
1. The SAAMI print says cartridge length to datum line between shoulder and neck is 1.5792 -0.0070.
2. Brass measured ranges from 1.573 to 1.576: all well within SAAMI cartridge tolerance.
3. The same print shows MIN. chamber to be 1.5792 and MAX. chamber to be 1.5892.
4. Both PTG NO-Go's (250 Sav., 250 A.I.) are 1.570 measured with my Hornady headspace insert.
5. Solution: add spacers to base to fit SAAMI minimum chamber.
THE STORY:
After reading tons of threads about the 250 Savage Ackley Improved cartridge, and being one that loves to dabble with "more from less"(efficiency, mileage) and more bang for the buck, I decided to make it my second "wildcat" project and my first one involving the need to ream a chamber to an Ackley Improved, and/or, fire-forming to a final cartridge size. The "Popular parent spawns insanely popular child (22-250), parent dies and child thrives" scenario makes it a fun tounge-in-cheek wildcat for me. ("obsolete" 250 Savage cartridge, plus a modified chamber, with an endless supply of emergency brass available). I found a source of Jamison 250 brass coincidently with an
E.R. Shaw Savage 110 Series Small Shank 250 Savage Factory Contour 1 in 10" Twist 24" Chrome Moly Blue barrel at Midway-USA for the price of a cheap blank, and happily ordered both, along with both the 250 Sav. and Ackly Imp. No-go gauges, and Redding A.I. dies with 40* shoulder. This to go on a used Stevens 200 rifle previously in 243 Win. as the donor.
I've chosen to break-in the barrel in it's 250 Sav. chambering to get baseline numbers over my chrono before "improving" and fire-forming. So I screwed the barrel onto my donor Stevens action and proceeded with the process of headspacing, but when the bolt dropped on the NO-GO but NOT the virgin brass I immediately blamed the brass for being too large. I tested the 250 brass against my 22-250 brass, which I expected to be the same-- (SAAMI says otherwise)--and it was larger. The 22-250 brass was smaller by a couple thou. but still larger than the NO-GO gauge. Assuming the NO-GO to be true, I failed to check it against the SAAMI print. "Hmmm........I got it!! Maybe I could order a standard 250 Sav. full-length die, wait 2 weeks for delivery, and bump the shoulders back on the brand new brass to work with the NO-GO gauge. Then, and only then will I take actual measurements". Lol, I wish that part weren't true. But when "bumping" failed I was forced to search for the true answer.
Back online I went to study the SAAMI print this time, and just like Neo, it took me way too long to bend the spoon until I finally realized I could. It was easy once I understood that SAAMI says my NO-GO gauges are frauds. As such, they will ruin the day of anyone who just uses these without measuring them and not comparing them to brass also.
After putting down the bent spoon and face-palming my smoldering head, "Duh, I can simply add target dots(spacers) to the base of my NO-GO, like others do to their GO gauges, until it measures just longer than minimum SAAMI chamber and the bolt drops on brass but not the "NO-GO".
Am I the lucky "1 in a million" to get NO-GO gauges marked wrong? And both of them measure the same length.
Marlan

 

[XBBR Shooter]

Something doesn't jive.
First, you didn't say who made your gauges. PTG doesn't mark the actual length on the gauge - just "GO" or "NO GO" (which makes me crazy)... Forster marks the actual length on the gauge (so I buy Forster, even though I perfer PTG for their colour coding)... the statistical chances of you getting a defective headspace gauge is maybe 100,000 to 1, or thereabouts.
The statistical chances of you getting TWO defective headspace gauges are about eleventy kajillion to one.

Second, the "Hornady Headspace" gauge...

...isn't!

It used to be marketed and sold as a "Comparator" which is more accurate. THEN, if you zero'd on a headspace gauge, you could get accurate measurements on cases... but if you don't zero it on a known object, then you can be Waaaaaay off

I have TWO of these gauges. I suspected something was wrong with the first when it wouldn't read a headspace gauge, so I bought the second. Now I have two of them and neither will read a headspace gauge, nor will they read anything with the same error. So I first set them up with a real headspace gauge, zero the vernier, and then make my measurements.

Take a good magnifier and look at the edge of the hole that goes over the case shoulder.... you will see a crudely beveled chamfer - some a**hole has chamfered the bored holes to remove burrs after drilling. These "Bushings" should have been face lapped, and this edge should dead square, sharp enough to shave with.

This topic has been discussed to hell and back a year or two ago on this site - maybe do a search.

If your gauges do not have the actual measurement on them, then buy yourself a Forster, and start again.

And remember that you CAN find commercial brass that is outside of SAAMI.

And remember, this "science" has a lot of wiggle room in it. Don't loose your hair over it.

 

[ireload2]

Your Hornady gauge is not very good when used in that fashion because it probably has an edge break on the datum bushing that is .006 to .010 deep.
Set your HORNADY gage against the headspace gauge and turn the dial until you get the same dimension on the caliper as is marked on the gage. Then check your brass.
You have a much better probability of a winning lottery ticket blowing in the front door than you have of the gauge being wrong. You also have about 100% probability of the Hornady tool being off due to a chamfer on the bushing ring.

Also keep in mind that the DATUM circle diameter is .347 and unless you have a custom bushing you will have also some error due to the difference between the bushing diameter you are using and the correct .347 bushing.
If you happen to be using 22-250 gauges they will vary a little from the .250 gauge dimension because the shoulder angle is slightly different.
Make sure you use the correct gages to set the headspace.
Since you are reloading and shooting a wildcat why not check a case .308 case that has been formed in your FL die and use that case to help you match your chamber length to the length produced by your FL die. There is no factory ammo to fit, there is only your FL die. If your FL die is made by RCBS it will be about .002 shorter than the NO-GO gauge but longer than the go gauge.

 

[danny]

Are they Forster Gages?

Dsnny

 

[fguffey]

If your gauges do not have the actual measurement on them, then buy yourself a Forster, and start again.

Or do as I do, you need to learn to say fantastical; to understand how fantastic is applied you need a short finishing school course.

I can not believe there is a reloader, smith or machinist that can not measure the length of a go-gage or a no go-gage or a field reject length gage in thousandths. And then there are chambers, I measure the length of a chamber from the shoulder to the bolt face three different ways without a head space gage. Of course it is all made simpler for me because my cases do not have head space and every thing does not have head space and all tools are not head space tools.

Unbelievable! Fantastic: A head space gage is a transfer, the head space gage is a standard and we have a forum full of reloaders, bench resters and smiths that can not measure the length of a head space gage. And it gets worst, they can not ask how? And then it gets worst, they believe they have to purchase another tool and I have no ideal why they would do that, it seems it would only complicate their lives more with more variations and tolerances.

F. Guffey

 

[fguffey]

And remember that you CAN find commercial brass that is outside of SAAMI.

I have purchases cases from shooting ranges that had been shotin trashy old chambers. Brass that has been shot in trashy old chambers is my favorite brass because I am a reloader and my presses and dies have threads. Threads make it possible to adjust the ability of my press die and shell holder to return cases to minimum length or I can sized a case by adding length to the case body between the shoulder and case head. When it comes to the 30/06 case I can add .051" between the shoulder of the case to the case head by using 280 Remington cases.

They did not make an 8mm57 Mauser with a chamber that is too long from the shoulder of the chamber to the bolt face because I have 30/06 cases. The shoulder of the 30/06 is ahead of the 8mm57 shoulder by .127", with .127" to play with I can not miss.

F. Guffey

 

[ireload2]

Have a peanut.

Or do as I do, you need to learn to say fantastical; to understand how fantastic is applied you need a short finishing school course.

I can not believe there is a reloader, smith or machinist that can not measure the length of a go-gage or a no go-gage or a field reject length gage in thousandths. And then there are chambers, I measure the length of a chamber from the shoulder to the bolt face three different ways without a head space gage. Of course it is all made simpler for me because my cases do not have head space and every thing does not have head space and all tools are not head space tools.

Unbelievable! Fantastic: A head space gage is a transfer, the head space gage is a standard and we have a forum full of reloaders, bench resters and smiths that can not measure the length of a head space gage. And it gets worst, they can not ask how? And then it gets worst, they believe they have to purchase another tool and I have no ideal why they would do that, it seems it would only complicate their lives more with more variations and tolerances.

F. Guffey

 

[M-61]

What a shame Alan Turing is dead and Bletchly Park is closed. I know there is something hidden in these answers but I can't break it.

 

[fguffey]

I searched, but didn't find any threads discussing No-Go gauges that are smaller than virgin brass. So, here goes.
NUTSHELL:

After putting down the bent spoon and face-palming my smoldering head, "Duh, I can simply add target dots(spacers) to the base of my NO-GO, like others do to their GO gauges, until it measures just longer than minimum SAAMI chamber and the bolt drops on brass but not the "NO-GO".
Am I the lucky "1 in a million" to get NO-GO gauges marked wrong? And both of them measure the same length.
Marlan

Am I the lucky "1 in a million" to get NO-GO gauges marked wrong? And both of them measure the same length.

How can a gage be marked wrong? I would suggest you learn to verify, a reloader/bench rester that can verify and understands the concept of 'ZERO' can measure the length of a gage in thousandths.

F. Guffey

 

[ireload2]

>>>Am I the lucky "1 in a million" to get NO-GO gauges marked wrong? And both of them measure the same length.<<<
If you have another gunsmith head space gauge with a similar shoulder angle use the correct Hornady bushing diameter that goes with that gauge to set your caliper. For example a 6mm REm is 26 degrees only .50 degrees different than a .250 Savage.
Then measure your mystery gages. Then use trigonometry to solve for the length difference caused by using the wrong bushing diameter.

 

[ttfreestyle]

>>>Am I the lucky "1 in a million" to get NO-GO gauges marked wrong? And both of them measure the same length.<<<
If you have another gunsmith head space gauge with a similar shoulder angle use the correct Hornady bushing diameter that goes with that gauge to set your caliper. For example a 6mm REm is 26 degrees only .50 degrees different than a .250 Savage.
Then measure your mystery gages. Then use trigonometry to solve for the length difference caused by using the wrong bushing diameter.

No sir you are not the only one, I ordered a set of go and no go for a 6.5x47 lapua . One was marked red and the other was marked green but they were both GO gauges. I sent them back and they replaced the no go that was actually a go that was marked red like a no go. Had me confused as this was only my second barrel swap at the time.

 

[swd]

Send the gauges back and have them checked. In the mean time your building a wildcat, don't overcomplicate it. If that's the brass you want to use then headspace it to that brass and be done with it. .004"-.006" of crush fit generally works well. All fixed, go shoot.

 

[Zero333]

Hornady's modified OAL cases measure the same as a go-gauge. At least all the ones I have do.

I don't bother with no-go gauges. 1 pc of masking tape on the head of the go-gauge makes it 0.002" longer so 2 pcs of masking tape = 0.004" longer = no-go-gauge. Works perfectly every time.

And like others said, the Hornady headspace comparator inserts most of the time do not measure exactly on the same datum point, so they will not match saami measurements.

For example, 243w/260/7-08/308 go-gauge is labeled as 1.630" from base to datum, but with my hornady comparator it measure 1.619"

 

[dickn52]

What a shame Alan Turing is dead and Bletchly Park is closed. I know there is something hidden in these answers but I can't break it.

If you’re bored I have the fix. Go buy three baby pigs. Paint the numbers 1, 2 and 4 on their backs. Go to Wal-Mart and get a lounge chair out of the sporting goods section. Let the three pigs go inside the store, have a seat. Now watch security go nuts looking for #3.

 

[6MMsteve]

Have a peanut.

LOLOLOLOLOLOLOL I can't stop

 

[M-61]

If you’re bored I have the fix. Go buy three baby pigs. Paint the numbers 1, 2 and 4 on their backs. Go to Wal-Mart and get a lounge chair out of the sporting goods section. Let the three pigs go inside the store, have a seat. Now watch security go nuts looking for #3.

First steal a chicken, then..........

 

[marfish]

Thank you all for the informative responses.
Ireload2 & XBBR shooter: Thanks for clarifying the measurements up. I need to quit assuming some things. As I read you, in order for the Hornady comparators to get me close, they have to have a sharp face-to-bore edge that is true to the .347 sized bore. Only then can they be properly zero'd out.
Fguffy: I always look for your hidden gems.
Freestyle: Thanks for acknowledging that I'm not crazy. lol.
SWD: that's what I was thinking- don't overthink and just use the brass as-is in a 'custom' chamber until that gets "improved".

1. The gauges are indeed Pacific Tool....
2. Indeed I am using the "comparators" and should have realized that they cannot be relied on for exact measurements, although this one has a rather sharp face. My others are chamfered.
3. My mistake, I used a once-fired 22-250 to compare to the 250 Sav. The virgin Nosler 22-250 brass measures 0.010 shorter than the virgin Jamison 250 Sav. brass at the same point using the comparator.
4. I just read PTG's description of the Ackley chamber Go and NO-GO setup on their website. He used the original chamber "GO" gauge as the new "NO-GO" to shorten the chamber 0.004 (same neck angle as the old). The new Ackley "GO" gauge is another 0.004 shorter to ensure that the new datum line crushes on the neck juncture of standard cartridges for fire-forming into the "improved".
What this tells me:
5. The standard "GO" is equal to the Ackley "NO-GO" except for diameter.
6. My standard 250 "NO-GO" gauge is equal to my 250 Ack. imp., "NO-GO". They should not be equal. One must be wrong since they cannot both measure the the same.
7. What I should have ordered were standard "GO" and "NO-GO" and an Ackley "GO". That would have provided me with all 4 gauge measurements. It looks like what I have is a functionally standard "GO" and Ackley "NO-GO".
Having spelled out what is what, has helped me immensely. Thank you all for pitching in.

Question to Ireload2: Sizing the .308 Win. to check for size with 250 Savage? I may be missing something else important here but, how/why would I shrink a 0.055 longer/wider cartridge to do the checks with? Wouldn't I need an arbor press: something to get some real crushing power? And wouldn't the shoulders buckle in my RCBS 250 Sav. FL die? How much larger brass can I shorten to make 250 Sav.?
To all:
I accept that since this is functionally a "wild cat" and I can either up-size 22-250 brass and fire-form it, or use re-sized 6.5mm Creedmore once the chamber is "improved", if I cannot find virgin 250 Savage brass to fireform. But for now, I am dealing with the standard 250 and should be able to proceed with the headspacing I have.

 

[fguffey]

7. What I should have ordered were standard "GO" and "NO-GO" and an Ackley "GO". That would have provided me with all 4 gauge measurements. It looks like what I have is a functionally standard "GO" and Ackley "NO-GO".

Or you could learn to use the no go-go gage for both measurements. Or you could modify the go-gage and turn it into a go to infinity gage.

F. Guffey

 

[swd]

Or you could modify the go-gage and turn it into a go to infinity gage.

F. Guffey

Is that sort of like an air gauge?
I saw you in a spaghetti western Sautuday. It didn't go well for you.

 

[marfish]

So, I have put about 100 rounds through the barrel now in the 250 Sav. standard config. to break it in, and it is working quite well. Brass fits nicely and with 75 grain Sierra bullets I'm getting about 3150 fps. Need to chrono some 100's for a baseline before "improving" the chamber.