When Headspace Is Off

[DaveInOroValley]

My understanding is that the gunsmith can open up the chamber a bit with a special tool?

I've read about many methods people do I guess dependent on what direction you have to go will make the difference?

[gunboat]

With a rimless cartridge only if it is too short -- which is not likely.
If rimless headspace is too long - beyond field -- the usual fix is to set the barrel back a thread or two and rechamber -

[swifty]

When you say "headspace is off", do you mean too short or too long or something else? Repair of incorrect headspace varies from model of gun and type of problem.

[Ryan in SD]

With a rimless cartridge only if it is too short -- which is not likely.
If rimless headspace is too long - beyond field -- the usual fix is to set the barrel back a thread or two and rechamber -

Why rechamber? It may need to be screwed in a little, I dont see how a chamber can evaporate at the end

[ArticleTheFourth]

Why rechamber? It may need to be screwed in a little, I dont see how a chamber can evaporate at the end

I think he is thinking of timing the sights on the barrel so that they are vertical. If you don't have barrel mounted sights then you can (usually, but not all the time) just grind the proper amount of material off the end of the barrel and reinstall. If still too long, take a bit more off until go-gauge fits.

If you take off too much, time to get a new reamer or take to gunsmith with proper chamber reamer.

[swifty]

...I don't see how a chamber can evaporate at the end.

Yup, you are correct. It's the other end...the metal in the lockup area of the receiver and the bolt or locking block compresses and/or wears. Replace bolts not checked, etc. etc. etc. can all lead to too much headspace. Headspace is measured in 0.001" and it does not take many to have issues.

[Mikeb]

First , do you understand that too much headspace is bad because the brass stretches to fit the chamber and this can cause head separation and the release of hot gasses in the shooters face.
One way to "live with it is to fireform the brass to fit the chamber. This is not recomended for auto loaders.
take care
Mike

[Sailormilan2]

Sometimes, just changing the bolt can change or fix headspace problems. A new bolt can lengthen or shorten headspace.

[Datamancer]

Sometimes, just changing the bolt can change or fix headspace problems. A new bolt can lengthen or shorten headspace.

Yeah, I'd agree that it would probably be easier to fix a headspace issue at the bolt head rather than modify the receiver.

-~D~-

[knucklehead0202]

Sometimes, just changing the bolt can change or fix headspace problems. A new bolt can lengthen or shorten headspace.

+1 ask an old british armorer, lol.

[v/dBrink]

My understanding is that the gunsmith can open up the chamber a bit with a special tool?

Incorrect.

http://www.cruffler.com/trivia-October99.html

[v/dBrink]

Sometimes, just changing the bolt can change or fix headspace problems. A new bolt can lengthen or shorten headspace.

This does not solve the problem that created excessive headspace in the first place. Add to that, you're not a gunsmith or armorer. Swapping bolts is very ill advised.

http://www.cruffler.com/trivia-October99.html

[v/dBrink]

Yeah, I'd agree that it would probably be easier to fix a headspace issue at the bolt head rather than modify the receiver.

What if.... the excessive headspace was the result of bolt lug setback? How would doing anything with the bolt fix the problem?

(hint.. it wouldn't)

http://www.cruffler.com/trivia-October99.html

[v/dBrink]

In a Mauser bolt action rifle.....

You drop in a field gauge and the bolt closes. What does this mean?

One of a couple causes.

1- receiver has stretched.

2- the bolt lug races in the receiver were too soft or have had 200,000+ rounds of ammo fired in the last 80-100 years and the lugs have "set back" into the lug races. This isn't always detectable from using headspace gauges.

How to correct lug setback?

You don't. The service life of the rifle is at it's end.

You can lap the bolt lug races but in doing so you *will* cut through the thin case hardening of the receiver. The experts all recommend re-case hardening of the receiver after lug race re-surfacing. $$$$$$$

What happens if you ignore this issue of lug race setback? Eventually it could well result in a fractured receiver or catastrophic failure. At the least it could result in case head separation which tends to dump large amounts of high pressure gas a couple inches FROM YOUR FACE. You could get hurt or dead.

What military armorers do does not count in 2011. You and your pal JoeBob are not military armorers and your wife and two kids would appreciate it if you didn't injure yourself doing stooopid things you read about on the 'net.

Get some book learning on headspace and stop spreading BS. Hatcher's Notebook has an excellent chapter on headspace and you can find it in PDF format online for FREE. Procure said book and read it cover to cover. It's about guns and ammo and shooting. It's cool.

p.s. Anybody who tells you it's ok to check headspace with scotch tape on the back of a cartridge or aluminum beer can should be avoided. You check headspace with headspace gauges. Nothing else.

Funniest headspace story I ever heard:

Dude take his rifle into the gunshop and asks the "gunsmith" to check the headspace. The "gunsmith" takes out the bolt and sticks his finger into the breech of the action. Hands it back to the customer and says, "headspace is fine".

http://www.cruffler.com/trivia-October99.html

This is a 1895 Chilean Mauser that was converted to 7.62x51 Nato. The bolt lugs have "set back" into the lug races. Can you understand how a headspace gauge check might not expose this problem? It's because the bolt lugs have to go up and past a high spot on the lug races before they drop down into the "set back" area. You get a false reading.





By doing a little Photoshop enhancement something was revealed...

The lower lug was doing most of the breech locking. One lug was carrying most of the load. This can be extremely dangerous when that one lug FAILS. It tends to sheer off the other lug when the first lug gives way. The bolt goes straight back into the shooters face. Sometimes it kills the shooter. Sometimes it only causes him to loose his right eyeball.

Anybody who uses the words "scotch tape" and "headspace" in the same sentence is going to get laughed at.

[Sailormilan2]

What v/dbrink says is pretty much correct. However, the receiver may have a mismatched bolt that was never headspaced. If that is the case, then there is a chance that replacing the bolt may fix the problem. I have done this on one Mauser.
Also, on semi autos like M1 Carbines and M1 Garands, the bolt lugs tend to wear before the receiver does. So, it a rifle developes long headspace, often times a new(newer) bolt can fix the problem. In both cases(Garands and Carbines), later bolts were made "longer" to correct for worn receiver/bolt issues.
In an M1A, you have a similar situation. However, with the Chinese made Polys, they are built long to NATO specs, which is longer than commercial SAAMI specs. Often times just installing a USGI bolt will correct the long headspace.
HRA, SA, and Win bolts tend to be easier to do. Many TRW bolts were made longer as replacement bolts to correct for estimated receiver wear. Wear that never happened, so fitting TRW bolts to Chinese receivers is more involved.