Headspace "adjustment?" in a bolt action...

[Glockdaddy]

OK, be nice...this may be a dumb question

Can you adjust a rifle for excessive headspace??

I have a Swedish Mauser CG63 that has a custom bull barrel installed. This barrel has very good lands and grooves, I don't think it was shot nearly as much as the rest of the action seems to show. This was a target rifle and this barrel was obviously added "later in life" with this rifle.

This gun shoots great, but I found that it fails the NoGo test. (Yes, I shot it without testing first. My bad....) Haven't tried a Field Gauge yet....so I am asking if a gunsmith can set the barrel back to bring the headspace into Go range?

If this is impossible am I :banghead:.....SOL?

Also, could I be missing one thing....bolt length? I say this because the bolt from my 96 will not close on an empty chamber in this 63. This makes me think that the 63 has minimal headspace, but when the new barrel was installed the bolt was modified to adjust the space and maybe they went to far? Those of you who really know about this can certainly help a newbie who is trying to learn. Thanks.....

 

[rcmodel]

It would be very unusual for anyone to "adjust" the bolt locking lugs to set headspace.

Other then lapping the bolt to the action, or "blueprinting" the action to square things up, it should never be done.

The normal procedure is to thread the barrel blank for proper fit on the receiver, then cut the chamber with a roughing reamer & finish reamer.
(or deepen the chamber slightly with a finish reamer if the barrel was already rough chambered by the barrel maker)

In your case, a gunsmith could easily measure the amount of excess headspace, then remove the barrel.

If your barrel has sights on it, it would need to be set back one thread, reinstalled, and the chamber re-cut with the finish reamer.

If no sights are present, the shoulder could be set back only enough to make the necessary correction without any chamber reamer being used. It would not matter if the barrel only turned a 1/4 turn, as there are no sights that have to end up on top.

rcmodel

 

[Jim Watson]

Are you handloading for it? If so, keep your brass separate and adjust the sizing die to not set the shoulders back any more than necessary for free chambering. If you can do this for several loadings without getting a casehead separation, march on. A little excess chamber headspace caused by minor misfit need not be a lot of trouble.

If the locking lugs or the shoulders in the receiver are beat back then it is a different matter and probably should not be shot at all.

 

[Glockdaddy]

Good points....

The sights on the barrel are globe sights that are mounted on a band, so removing and recentering is not an issue. The second point about reloading is well taken and I do plan on setting up to reload in the not so distant future. I assumed that I would probably load for each rifle differently any way.

Thanks for the input gentlemen.....

 

[Jim K]

Please quit using a NO-GO as a Field gauge. The NO-GO is a factory/gunsmith gauge, used when making or rebuilding a rifle.

It is common for a used rifle to fail the NO-GO test. Only a Field gauge will let you know if there is a problem.

It is like using a treadwear gauge on a tire. If you threw away your tires as soon as they had less tread than the factory spec called for, you would never get any use out of them and you would spend a lot of money.

Jim

 

[1911Tuner]

If the lugs or their recesses in the receiver are badly set back or worn...you can install a new semi-finished barrel and ream the chamber to set the headspace to the bare minimum and still have a dangerous headspace condition unless the barrel is a full-fit blank, and you can set the barrel shoulder to move the barrel face closer to the bolt, and then ream the chamber to finished spec. In other words...the riflesmith needs to know what he's up against.

 

[Glockdaddy]

"Please quit using a NO-GO as a Field gauge. The NO-GO is a factory/gunsmith gauge, used when making or rebuilding a rifle. "

THAT IS WHAT I NEEDED TO HEAR, THANK-YOU!

Being relatively new to working with older rifles, I have been following the typical advice of how to check headspace, etc. The use of a Field Gauge is not mentioned as much in the discussions I have read and I was unsure of the value of utilizing the Field Gauge. This makes perfect sense and follows some other advice I was given regarding the headspace variances in military rifles as well.

Thanks again for all of the comments....good information.

 

[Jim K]

To continue (or overdo) the tire comparison, the Field gauge, sometimes called the Field Reject gauge, is like the wear ridges in a tire tread. When you see them, you don't panic and stop in the middle of the road, but you do start looking at tire ads in the paper.

Of course, with an old or milsurp rifle, there is no way of knowing just how many rounds ago it would have failed a Field gauge test, so it is best to assume that any failure indicates a problem. Badly stretched or separated cases mean headspace is definitely excessive and the rifle should not be fired until it is determined if correction is possible.

Jim

 

[1911Tuner]

Of course, with an old or milsurp rifle, there is no way of knowing just how many rounds ago it would have failed a Field gauge test, so it is best to assume that any failure indicates a problem.

I'm glad that somebody (else) came out and said that for the benefit of those who say that...because they've never had a problem with an old Mil-Surp rifle...nobody will.

I'd venture a guess that if they actually knew what the headspace was in most of'em, they'd hang'em on the wall.

One of the first and most obvious signs is a badly flattened primer with ammo that doesn't exhibit the same in another rifle...or known safe handloads that do it.

The next thing to look for is the bright ring around the case on the first firing. If you have either of these symptoms...Hang it on the wall or get thee to a smith before you fire it again. The eyes that you save will probably be your own.

 

[Jim K]

I have seen several milsurp rifles that had excess headspace, including one K.98k that routinely had case separation. But in the normal course of things, those rifles came out of military depots where they had been held as a war reserve. Most had been checked and repaired as needed before storage.

Even so, there is often no knowledge of what happened to them between then and now, so caution is not a bad idea.

Jim

 

[ralfus]

Is there any chance the target barrel was installed in another country? This is probably a moot point since the custom barrel should have been installed to near minimum headspace but more a question of which headspace gauges were used when the barrel was installed. Swedish military headspace specs are different and looser than SAAMI specs, much the same as .308Win vs 7.62NATO. Many years ago when an importer brought in a large quantity of Swedes they used Swedish military gauges to inspect the headspace before distributing them. Then some purchasers of the rifles later had the headspace checked by their local gunsmith with his SAAMI gauges and the rifle "failed"

Any discussion of headspacing a 6.5x55 should involve reading this link as a primer: http://www.rebooty.com/~dutchman/headspace.html

 

[Glockdaddy]

Good Point, Ralfus

My dealer told me that the military headspace gauges are different than SAAMI as well.

EXCELLENT ARTICLE!! GREAT REFERENCE RESOURCE!!

 

[Jim Watson]

Good information.

But just because it likely meets Swedish specifications does not mean you will not have to take the longer chamber into account if you handload for it with US dies and components.

 

[ralfus]

"But just because it likely meets Swedish specifications does not mean you will not have to take the longer chamber into account if you handload for it with US dies and components. "

Very true. I stumbled on the headspace article after trading my Swede to a friend that shot it with PMC ammo and he got partial head seperations.