I have a 7 X 57 mauser (sporterized real mauser action) of some sort that I aquired. I has a pretty piece of wood and I like the action. Thinking of resurecting it into a nice rifle. I shot it to see if it would shoot anywhere near accurate to begin with and to decide if I needed to re-barrel.

It did not shoot terrible. 3" groups. Not terrible I did not think for an unbedded stock with barrel pressure everywhere and poorly fitted stock.

But to my real question, about a 1/4" up from the rim, the cases come out slightly bulged.

What does this mean???

Sounds like a worn or oversize camber or

too much pressure or ---------

You get the idea.

Pics and micrometer measurements of the case (before and after firing) would help.

Is the bulge concentric or one sided?

I have a beautiful 1903 MS with a worn area near the rear of the chamber that results in a slight unilateral bulge.


If it is concentric does it show a bright pressure line?

You may have a short throat or tight bore or oversize chamber 0r---



A chamber cast an a barrel slugging sound in order.

Actually easy to do.

If the chamber is bad the barrel may be able to be set back enough to clean it up--etc

That is the more or less normal location of what is commonly called the "pressure ring". It represents the point at which the case walls near the head are thick enough to resist deformation from the pressure generated at firing -- forward of that point the case walls are thin enough that they expand to take the size and shape of the chamber walls. If the bulge is particularly obvious, it means that the chamber is somewhat oversized compared to the brass case. Whether it is an "oversized chamber" or an "undersized case" is somewhat irrelavant. You can start by checking the diameter of the case heads, which should be somewhere from .469" to .473" at the rim (and the portion of the case immediately in front of the extractor groove.) If the cases are significantly smaller than this dimension, your "bulging" problem can be solved by finding cases of larger dimension. However, if your cases are close to standard, then that would indicate that your chamber is somewhat oversized. However, other than showing a somewhat pronounced bulge upon firing, such a situation doesn't necessarily create a problem.

reminds me of an old m1 carbine i got out of the dcm once many moons ago. the chamber was so bulged that i had to beat the case out with a rod. even then it looks like hilarys ass

quote:

Is the bulge concentric or one sided?

It is NOT concentric but one-sided. I don't see any other signs of pressure. The primer is not even flat. The bolt opens easy. The case just flings out as this action is buttery smooth.

Sloppy chamber. Set the barrel back & rechamber. End of story.

quote:

Originally posted by ledvm:

quote:

Is the bulge concentric or one sided?

It is NOT concentric but one-sided. I don't see any other signs of pressure. The primer is not even flat. The bolt opens easy. The case just flings out as this action is buttery smooth.

Well you have a choice to make- if it is a simple barrel--no full length rib,folding leaf sights, makers marks, effecting value you loose by altering---set it back. (or re-barrel)

If the bulge is not "too large"
you might consider leaving well enough alone---
As in my case the little MS prototype has all the above features--but it still shoots lights out-- the case life drops in number of reloads but I've learned to adapt. You just need to monitor your cases carefully.

Again, micrometer your cases, then talk it over with a competent gunsmith and then decide.

It has a funky barrel that has 2 "steps" down in diameter. One 2" from action and one halfway down the barrel. The barrel is only 22" long now.

Think I will rebarrel to a good 24" barrel.

O.K. The "stepped barrel" is probably the original military barrel. This was standard Mauser design. Much thought out and works good. Just looks weird to modern thinking.

b). If it is the original barrel it may have a "large" chamber, not uncommon, for use with any ammo in any condition. I would shoot the gun and maybe relieve the stock a bit. If it shoots good this is not a huge problem. Cases, resized full length, wear out a trifle faster. The other thing to worry about, if the rifle is developing headspace... You might not want to spend money on it. Got a date for the action? Mr. De Haas does not recommend working on Mauser actions pre 1920 or 1930 to be careful. Older steel. Your bucks... Often a date will be found with the proof mark under the front ring with wood removed, where the barrel screws in.

But, your call. Enjoy.

Cock on open , cock on close, small ring, large ring, etc--check your action type and age before yo put too much dinero into the project.

quote:

Sloppy chamber. Set the barrel back & rechamber. End of story.

Certainly sounds as though you've a egg-shaped, out-of-round chamber. Sloppy chambering job. Had similar after a Hack exchanged a barrel.

You can live with it or have the barrel set-back but that will affect the barrel steps and the stock.

quote:

Cock on open , cock on close, small ring, large ring, etc--check your action type

It cocks on closing. Don't know what large ring small ring means. Help me out here please.

Lane,

It sounds as if it is an original 7mm. Since it cocks on closing, it is likely a Model 93 or Model 95 -- sometimes known as the "Spanish" Mauser, although these actions were used in rifles built for a number of countries around the world, particularly in South America. They are not generally regarded as being as desirable as the M98 (cock on opening). Heat treat and metallurgy varies.

I wouldn't spend any money on it, but rather keep it as it is and shoot it as it suits you. Ignore the bulged cases -- those are to be expected with military chambers made large enough to cram a cartridge into along with mud, leaves, and grass.

Cock on closing is almost exclusively a small ring, the bolt will also not have a third lug toward the back.

Large ring/ small ring has to do with action diameter.

( A sporterized 93,95,96 small ring could have been modified to cock on open but not typically, but no third lug should be present.)

The 98's cock on open and are mostly large rings, there were a few varieties and markedly fewer numbers of small ring 98's made.

Pictures and markings would help.

In general the 93 and 95 are less desirable and " less safe" than the other small rings (96, and the 98 variants in particular)

Again before you toss money at it get some knowledgable person to inspect.

I hear you stonecreek! But...I kind of like the action. Is it dangerous? What would be wrong with fixing it up with a new barrel and fixing the stock properly? My dad wants a real mauser action chambered in 7 X 57. It is just a project. What are the negatives to the action???

Sloppy chamber. Set the barrel back & rechamber. End of story.(quote)
I had a 91 Mauser that did this. Set the barrel back or get a new tube for it. That is what is needed at this point.

Somebody please comment on my questions above about the action.

quote:

Originally posted by ledvm:
Somebody please comment on my questions above about the action.

Well its tough not knowing exactly what it is and what shape its in--
Kinda like "Doc, my dog's sick. What's wrong?" 'cept you can't see the dog and thats all the info.

The small rings were built in many locations and are weaker than 98's.

The metallurgy and heat treating varies by location so some are "worse" than others.

I have built many sporters on small rings.

I prefer 98 small rings, followed by 96 Swedes and 95's and 93's lagging behind.

You really need to have the "dog" taken to the "Doc" and have someone look at it that truly knows the ins and outs of these actions.

We are just tryin' to give good and more importantly SAFE advice.

lots of good explanaitions here.
to me it sounds like a slightly oversized chamber, may not bad enough to be a problem. i would guess that the extractor is holding the case over to left side of the chamber resulting in the lopsided bulge. next time you shoot it, watch to see if the bulge is in line with the claw on the extractor as it comes out of the chamber . this was actually kind of common on 93's -96's. your gun may still have good headspace, so if the bulge isn't so big that it splits cases (appearently not) it shouldn't get any worse. the only problem is that it will cause case life to be short. setting the barrel back enough to clean up with a rechamber might not be possible with the original mauser barrel as you might have to have more material removed than the thickness of the barrel's shoulder flange that sits against the action will allow.
the 7x57 is an excellent round and if it is a mod.96, although not as good as a 98 in general, it's certainly worth keeping as a hunting gun. should you decide to re-barrel the gun, you can get a perfectly servicable hunting quality barrel for around 100 bucks. i personally wouldn't put a high dollar barrel on a 96, you won't get your money back out of it if you sell it. the low dollar barrel won't do any worse than the original mauser barrel, probably a bit better.

I will take pics of the action and post them as well as the cases.

Any particular view of the action you want?

I have had a similiar experience "one sided bulge on cartridge". I came to the conclusion it was a bad "finish" chambering job - slightly off centre at the base. Are your primers also being hit ever so slightly off centre? - mine were. Just to add, this was on a Sako HB varminter in .244, didn't seem to affect accuracy but reloading was a different story. I had to full lenght size every time and only reloaded 3 times after having the base come right off a round reloaded more than 3 times. FWIW --- John303

quote:

Originally posted by ledvm:
I will take pics of the action and post them as well as the cases.

Any particular view of the action you want?

Since its been sporterized :

Left side of receiver (for gas vent holes, markings, etc)

The top of the receiver ring (with the mounts removed will help if the crest was not milled off)

Picture of the boltface (93 has a square bottom face)

Picture of the bolt Latch Cut (shoulder cut)
Right rear of receiver ( with bolt removed) (93's do not have this)

Right side of receiver ring(markings)

Remember just getting the action Identified doesn't tell the whole story about strength,
though it does help.

The action should also be inspected by a qualified person before proceeding in a conversion or handloading to "modern" pressures.

(Factory USA " standard " loads in 8x57 and 7x57 are lower pressure than many European loads . )

ledvm,

I believe merlinron may have hit the nail on the head. With most calibers you can have as much as .011" clearence between min cartridge and max chamber dimensions and still be within spec. In many rifles the extractor will force the round to the opposite side causing the bulge to be on one side as well as the primer indent to look off center. As long as the chamber is within spec you should be good to go.

Headache

It has what is known as a "generous" chamber. This is not too unusual for ex-military rifles. Unless really excessive, it is nothing to worry about.

quote:

Originally posted by ledvm:
I will take pics of the action and post them as well as the cases.

Any particular view of the action you want?

Did you get this sorted out to your satisfaction?

quote:

Picture of the boltface (93 has a square bottom face)

Duggaboye,
It does have a square bottom face on the boltface.

Does that mean for sure it is a 93?

measure between the screws on the boittom of the action [by the trigger guard] if it's about 4" it's most likely a 93.
no big deal, as american ammo is made just for these guns as their pressures are held below 45k.
you could pick up an adams and bennet bbl from midway for about 100 bucks and have it installed and finish chambered by a gunsmith for another 100.
it would/should shoot some better, and have a better chamber to boot.

quote:

Originally posted by ledvm:

quote:

Picture of the boltface (93 has a square bottom face)

Duggaboye,
It does have a square bottom face on the boltface.

Does that mean for sure it is a 93?

99.9%

There were a few others,(esp. Boer's) they just aren't seen much any more.
Commonly expect it to be a 93
This is where the markings(as mentioned above) come into play