Help from the Mauser Experts needed

[bob q]

[QUOTE=browningautorifle;457667]Here's something written in a local hunting forum... Thing is, your bore is big enough to take them. I'd be with you...and try them.
Sounds like before you had .318 diameter bullets and they were barely engaging.

Both vintage military and sporterized versions of the Mauser Model 1898 bolt action rifle are still readily available on the used gun market but, it should be noted that older versions of these rifles are designed to fire a .318 caliber bullet and these rifles are designated as having “J” bores whereas, newer versions of these rifles are designed to fire a .323 caliber bullet and these rifles are designated as having “S” bores.
American

A lot of incorrect information here. The German military NEVER used a .318 groove bore size . The German military never called any bore size J or S . The actual bore size on any German military rifle from 1890 1/2 was .311 with a groove size of .321 until 1896 1/2 when it was changed to .323 + , called the Z bore change by the German military . The bore size of .311 was always right on but the groove size could [ and did ] vary from .323 up to .326 . They did not care about the groove size as long as it was above .323 . The S BULLET was made at .321 with a .323 skirt so it could work in all rifles , .321 and .323 . It had a open flat base to let it expand to seal with the larger groove rifles . So for modern shooting with modern bullets a flat base bullet or a larger dia boat tail is needed for accurate shooting . The land dia is more important than the groove to get a good bite on the bullet , so a long round nose [ lots of bearing surface to stay straight in the bore ] .323 bullet with a flat base will solve most .325 + groove barrel problems .

[browningautorifle]

A lot of incorrect information here.

Sure thing, whatever you say. Not written by me in the first place, at least I told him that. As always, you're the expert (You say)...

[bob q]

Well I guess all my original German test documents , 80 Gew-88 rifles , original ammo are not real ?

[jsne]

Ok
What I need to know:
If i have a load with .327 bullets and in a mistake
Load them in my smallest Mauser .3225
What could happen?
I always full size my 8x57 not having trouble with
Any of my Mausers.
Yes I could neck size and mark this to avoid any risk

Or I could fit a barrel on the rifle who not have
This “problem”

The rifle is bought as a shooter and not a collectible item.
And I still have a original barrel for it.

Jsne

[Patrick Chadwick]

Q: If i have a load with .327 bullets and in a mistake Load them in my smallest Mauser .3225 What could happen?

A: A very serious overpressure - maybe chamber ringing, maybe shattered action.

[Steve1152]

I hope someone can help me. I am Tagging onto this thread. I have a K98 all matching numbers J P Saur 1940. I have a set of bore gauges and want to know the correct bore diameter and degrees of wear to the point of being worn out. Currently the bore is measuring 7.95mm or .313. Thanks for any help and advice.

[Patrick Chadwick]

"Correct" is not a word that you will find in standards documentation, but a somewhat subjective adjective, popular with collectors, that already implies a judgement.

The "Masstefeln für Handfeuerwaffen und Munition" - which is the legally binding set of dimensions that would be used by a proof house - gives the following
for the chambering 8x57JS:

Felddurchmesser (diameter across lands) 7.89mm
Zugdurchmesser (groove diameter) 8.20mm

These are minimum dimensions.

[Patrick Chadwick]

It seems that your bore is seriously worn. I have not yet found any official definition of maximum land and groove diameters. Until they turn up, let's look at it from a practical viewpoint.

"Shot out" is not an official definition that you will find in any set of standards. But for a specific rifle it may be defined as that level of wear at which the rifle no longer performs satisfactorily. There are perhaps 3 major factors. A badly worn barrel will usually have a combination of these factors.

1) Throat erosion. Results in the bullet having a free flight before it properly engages the lands. Since the cartridge neck has some play in the chamber, it sits on the bottom, and the bullet emerges in the lower portion of the space available. It is thus engraved on the skew and will tend to have a corkscrewing motion when it leaves the barrel. Depending on the amount of wear, this can result in anything in the spectrum enlarged grouping through keyholing to missing the target entirely at what would be considered point-blank ranges. Hence the general advice to keep the bullet seated as far up the throat as is sensible, and to avoid boat-tailed bullets in military rifles, as these rifles tend to have generous throats by comparison with modern standards. A standard test method is to drop in a bullet of your choice into the throat and measure how far it enters the barrel, i.e. to measure the overall cartridge length that would be required for the bullet to engage before it has left the neck of the cartridge If that position is beyond the max. OAL of the cartridge, then you have a problem. Mauser rifles generally have a very long throat, so you need to look for a bullet with a long cylindrical section. Don't forget that the designation 8x57JS stands for 8x57 cartridge for Infantry (the J) rifle using S (spitzer) bullets. Not boat-tails!

2) Enlarged land diameter. Reduces the engagement of the bullet in the rifling. No immediately disastrous effect until the stage is reached at which the bullet is no longer being grasped by the rifling and is stripped by the grooves without being rotated. With lead bullets this results in immediate serious leading of the barrel and disastrous grouping, as you are effectively firing a smooth-bore gun. I have not experienced this with jacketed bullets, but I have experienced it with copper-plated bullets, with recovered bullets showing that the copper had been stripped off the lead.

3) Enlarged groove diameter. Assuming that all other things are equal - which, in practice, they never are - this allows blow-by of hot gases and is a factor in increasing throat erosion. With jacketed bullets, the only remedy is to use a bullet that is as close to the groove diameter as possible or even a tiny bit (0.001") larger. This trick is limited by the available space for the cartridge neck in the chamber. With lead bullets you have more freedom, as they upset to some degree in the throat, so that even if the largest possible bullet is too small, you can gain a bit more obturation by using a slightly softer lead alloy.

Summarizing:
a) Measure the groove diameter.
b) Select a bullet that is equal to this diameter or + 0.001
c) Select a bullet that has a long cylindrical section, to keep the base guided by the cartridge neck as long as possible
d) Check that you can actually chamber a cartridge loaded with such a bullet.

I hope you can find a solution!

[Steve1152]

Patrick



Very late, but thanks very mcuh for your reply. I have to conclude the barrel is worn and needs replacing!!