What is a headspace tester ?

[CygnusX1]

In a bolt rifle, the bolt pushes the cartridge into the chamber and keeps it there tight. There is no room between the bolt and cartridge so I don't understand what is being measured

The name implies it can measure the space but if there was a space, it would be dangerous to fire this rifle
Unless this thing measures spacing in the order of 0.001 inch

 

[PinesAndProjectiles]

But there is.

When you fire a round, the brass will expand to fit the chamber, but then will shrink a bit, but will still be larger than before it was fired.

During the sizing process, you are bumping the shoulder back about .001-.002 inches.

So yes, the brass is smaller than your chamber by more than .001" and is still safe to fire.

 

[RTH1800]

There is a space, case should not be “tight”.

Secondly, you could call it a head distance gauge. It measures the distance from boltface to shoulder or to front of belt on belted cases.

 

[AFancyPenguin]

There is is space case should not be “tight”.

Secondly, you could call it a head distance gauge. It measures the distance from boltface to shoulder or to front of belt on belted cases.

What? Its just called a headspace gage. That's just what it is.

 

[RTH1800]

What? Its just called a headspace gage. That's just what it is.

Agree but I was trying to explain it in another term so that the OP would understand due to his apparent issue with the term headspace. The gauge actually measures distance from bolt face to shoulder, excess "space" is determined by the case size.

 

[AFancyPenguin]

Agree but I was trying to explain it in another term so that the OP would understand due to his apparent issue with the term headspace. The gauge actually measures distance from bolt face to shoulder, excess "space" is determined by the case size.

I got ya. I was brave to attempt to understand what was going on before my coffee

 

[b6graham]

I got ya. I was brave to attempt to understand what was going on before my coffee

one does not simply try to understand rth before their morning coffee

 

[CygnusX1]

But there is.

When you fire a round, the brass will expand to fit the chamber, but then will shrink a bit, but will still be larger than before it was fired.

During the sizing process, you are bumping the shoulder back about .001-.002 inches.

So yes, the brass is smaller than your chamber by more than .001" and is still safe to fire.

I'll be dammed...
I did not know the brass would expand.....
I just saw it tight and the bullet forced to go out
But it makes sense that the brass needs room to expand otherwise it would jam in the chamber.

I am not used to thinking in terms of 0.001 inch as "loose"

Thanks for your help guys !
I appreciate it

 

[Rocketvapor]

Actually 0.001" is pretty tight

 

[CygnusX1]

If the headspace gauge is that precice and "reads" thousands of and inch precision, then the chamber actually softened and changes size over time ?

Hard question: How much change does it take to have high pressure gas blow into the shooter's face ??

Fact: I own a WW1 0.303 Ross rifle and it shoots but I think I will buy a gauge just to see if it's borderline worn out

 

[Rocketvapor]

A headspace gauge is a solid chunk ground to represent the minimum headspace and is called Go-gauge.
Chambers can stretch and lugs can compress with age.
There are specifications for a NO-GO and FIELD gauge to check for this.
If a gun started out close to the Go specification then changed over time the Field spec would indicate it's worn out. Maybe in the 0.010 to 0.012" range.

There are chamber measuring devices that you set and read with a micrometer or caliber.
These allow one to set reloads to a desired "less than chamber" length based on cases fired in that exact chamber.
That might be 0.001" for benchrest to 0.003 for a semiauto.
Really tight chambers may or may not close on all commercial ammo which might have a range of 0.003, usually short but not always.

The two primary uses are checking for excessive/unsafe headspace, or setting reloaded cases to a desired shorterness to minimize stretch when fired. Repeated stretching, bumping back to size when reloading, stretching the next time, over and over wears out brass and cause failure.

 

[CygnusX1]

Thank you Rocketvapour !
This is impressive !!