rifle headspace question

[Brother_Love]

We have a 1908 Brazilian 7x57 rifle that the bolt closes on the no-go gauge. When a .002" shim is added the bolt will not close. Is it safe to shoot? From what I have read I am OK but I wanted to ask for other opinions. Thanks

 

[DGW1949]

In a word, no.
However....Some folks will tell you to use some light handloads to "fireform" the case to your chamber and afterwards, neck-size (only) them cases for use in that particular rifle.

Personaly, I like to err on the side of safety.
When in doubt, don't.

DGW

 

[Snake45]

We have a 1908 Brazilian 7x57 rifle that the bolt closes on the no-go gauge. When a .002" shim is added the bolt will not close. Is it safe to shoot? From what I have read I am OK but I wanted to ask for other opinions. Thanks

Depends on the exact specs for that cartridge.

"No-go" gauge is what it's not supposed to close on when brand new. The one you want to worry about is called the Field Reject Gauge, which is what it's not supposed to close on ever and be safe to shoot.

What are the specs for the No-Go and Field Reject gauges for 7x57? If the FR spec is more than .002 over the No-Go spec, then you should be good--for a while, anyway.

(For example, for 7.62 NATO, the No-Go spec is 1.634 and the Field Reject spec is 1.6445, a difference of .0115, but I don't know what the specs for 7x57 are.)

 

[WOB]

It sounds like it could well be safe to shoot. There is no SAAMI standard for No-Go gauges. For bottle neck cartridges, most gauge makers make it about .006 larger than the SAAMI Go gage which is also the SAAMI minimum chamber spec. , 1.79047" The SAAMI chamber max. is 1.8047". This is also the so-called Field gauge length. The difference is .010". So, if your chamber is not quite .002" longer than the no-go cauge, it is likely about .008" longer than the Go gauge which still makes it less than the Field gauge. Your mileage may vary.

New ammo fired will stretch out to fit the chamber and if those cases are reloaded with a properly adjusted FL sizer die, they will perfectly safe to shoot from now on. If they are resized to factory minimum, case life will be short due to over working of the brass.

WOB

 

[Carry_Up]

In a word, no.
However....Some folks will tell you to use some light handloads to "fireform" the case to your chamber and afterwards, neck-size (only) them cases for use in that particular rifle. DGW

Aren't we mixing up accuracy with safety? Headspace tells you how much unsupported brass you have hanging in free air. Fireforming cartridges to match your chamber is done in the interest of obtaining match rifle accuracy, or perhaps extending the number of times you reload a certain piece of brass. Two totally different subjects.

Why should we analyze whether a no-go gauge is giving us useful information? Closing on a no-go rifle gauge means its time to get something fixed. Quote specifications for M16 headspace gauges if YOU are shooting the rifle.

Carry_Up

 

[Snake45]

Aren't we mixing up accuracy with safety? Headspace tells you how much unsupported brass you have hanging in free air. Fireforming cartridges to match your chamber is done in the interest of obtaining match rifle accuracy, or perhaps extending the number of times you reload a certain piece of brass. Two totally different subjects.

Carry_Up

Well, yes and no. Fire-forming and neck sizing (only) are usually discussed in terms of getting the most accuracy out of a rifle, but they are also topics that are useful when talking about shooting a rifle with generous or excessive headspace. In essence, you have sort of a "mini-wildcat" situation here, a "new" chambering with different specs (slightly) than factory or SAAMI. There's no reason you can't proceed in the same way with perfectly acceptable results.

 

[gunboat57]

My Brazilian Mauser in 7X57 has a tight chamber, meaning I must full length resize in order to be able to chamber my reloads.

My Remington RB #5 in 7X57 has a chamber that's, well, generous. I only neck size brass for that rifle. If I full resize and push the shoulder back each time the brass would continue to stretch on every firing and eventually the head will separate from the body. Not something I look forward to.

I do keep the loads on the mild side for the RB by the way.

 

[DGW1949]

In a word, no.
However....Some folks will tell you to use some light handloads to "fireform" the case to your chamber and afterwards, neck-size (only) them cases for use in that particular rifle. DGW

Aren't we mixing up accuracy with safety? Headspace tells you how much unsupported brass you have hanging in free air. Fireforming cartridges to match your chamber is done in the interest of obtaining match rifle accuracy, or perhaps extending the number of times you reload a certain piece of brass. Two totally different subjects.

Why should we analyze whether a no-go gauge is giving us useful information? Closing on a no-go rifle gauge means its time to get something fixed. Quote specifications for M16 headspace gauges if YOU are shooting the rifle.

Carry_Up

You missed my first sentance..... To be more specific, I don't, never have, never will recomend putting a gun into service which does not pass a simple go/no-go headspace check. That said though, there are folks out there that don't agree with me and have their own ways of getting around that particular delima. One of those ways was alluded to in my first post....and sure-nuff, we soon began to see my prediction show up in the thread.
Sorry, but I can't help you with the chamber specs for the Stoner platform. I don't shoot the things. I do however, hope this follow up to your concerns clears up my position on the matter at hand.

In other words, it seems that you and I are in agreement. :wink: .

DGW

 

[Precision32]

Most brass will stretch as much as 0.012" before the chance of case head separations accrue.

"GO" gauges are the MINIMUM headspace required. The "NO-GO" gauges are used when cutting the chamber, and tell you when you cut too much from the chamber. Properly headspaced rifles will have the headspace fall between the GO and NO-NO gauges.

IMHO, your rifle is safe to shoot.

 

[DeletedMember275]

IMHO, you should set your barrel back one thread and recut the chamber. That way you'll know that it's right.

 

[Mobuck]

You can solve this problem by expanding the 7mm neck to 7.62 by running new brass(lube inside of neck first) into a 308 win die. After the neck is expanded, size in a standard 7x57 sizing die until the bolt will close with a slightly noticeable amount of force. Load as is recommended for 98 model Mausers and enjoy. When resizing, do so only enough to close bolt w/o undue force(ie, the same die setting you used initially). I've loaded for some surplus Mausers that were way over spec on headspace using this method. It is not a problem since a correctly headspaced rifle won't chamber this ammo and it's no big deal even if you could force it into a normal chamber.

 

[Dan in MI]

Not casting stones in any direction here. I just find it interesting to see the different sides of experimenters and rule followers here.

 

[Precision32]

But what rules are being followed and what do you refer to as experiments?

 

[DGW1949]

But what rules are being followed and what do you refer to as experiments?

Seems rather obvious to me.
The "rule" is that a "no-go" headspace guage means what it says.
The "experimenters" are experimenting to see if they can get by with exessive headspace by making the cartridge-case stretch to fit.

My question would be;
Beings how the gun just swallowed a no-go gauge, how do you know how much more it might could still swallow?

I know, how about we just fire the gun and measure the brass. :shock: .

DGW

 

[Dan in MI]

How about I use different terms? Book loaders versus wildcatters. :wink:

Still not throwing stones just observing human nature.

 

[Snake45]

Beings how the gun just swallowed a no-go gauge, how do you know how much more it might could still swallow?

DGW

Excellent question/observation! The answer is: That's what the Field Reject gauge/specification is for.

Again, a No-Go gauge does NOT (necessarily) mean a rifle is unsafe to shoot. It just means that headspace is unacceptable for a new rifle or barrel. It also suggests (as does your question) that further investigation be done to find out how much excessive the headspace is. :wink:

 

[Precision32]

The use of "GO" and "NO-GO" gauges is during the final reaming of the chamber. "GO" tells the smith the the chamber meets minimum headspace. The "NO-GO" tells the smith to stop, he's cut enough.

Every rifle has a "Field Reject" dimension for headspace. For the 30-06 M1 the Field Reject is 0.008" longer, at 1.950," then the "GO" gauge at 1.942" for new rifles. It is 0.006" longer than the "NO-GO", at 1.944" for the same rifle.

The OP clearly stated that his chamber is 0.002" longer than the "NO-GO" gauge.

Again, the rifle is within industry standards and I would have no problem shooting that rifle.