Here's something I have heard but have no experience with.

I have heard that small ring large barrel thread Mauser 98s such as the Kar98 should be used with lower pressure cartridges, whereas small ring small thread M 98s such as Mexican Mausers, G33/40's, Brno 21's can safely be used with higher pressure cartridges (e.g., 270, 308).

What I would hope someone can answer is:

Don't both types of M98s described above have the same amount of metal around the cartridge? I think both are the same around the locking lug areas. It seems that what differs between the two is how close the barrel threads are to the outside of the receiver ring.

So if there is the same amount of metal around the cartridge, shouldn't they be similar with respect to what cartridges they can safely handle?

Thanks for any insights,

David

i believe it's the gas handling ability of the 98 that makes it suitable for more powerful cartridges.

The small ring large thread 98's are best reserved for lower pressure cartridges. Also, some actions are better than others.

There is a reason that the small ring small thread actions command a higher price.

in a very short answer-you calcualte stress by dividing by the cross sectional area. The thinner action ring cannot handle the stress, causing the ring to stretch. I think the small ring/large shank actions were discontinued even before WWI ended.

Given equal metalurgy why isn't it a toss-up relative to modern cartridge pressures? The large barrel shank does 95% of the work regardless of the receiver diameter, until the pressure causes enough elasticity or plasticity in the shank to stress the receiver? (My, I've learned some big words on AR!)

In other words short of a catastophic failure, is the total cross section that much more critical that the chamber wall thickness in the shank? I'm thinking of all the late production Husqvarna 1600 series rifles that are small shank but chambered in all the high pressure modern rounds. If we're limited to the older transitional Mausers then I have to agree.

The Kar98a small ring M98's are a good action; the 1917 and 1918 are better for full power 8 x 57 or even 30-06, but they are not ideal. Another huge factor with them is you have very little meat for scope base holes unless you drill into the barrel, which is not conducive to accuracy.

ETA: I am fairly certain that small ring Husky actions have .965" barrel shanks. The Kar 98a has 1.100" barrel shank. Smallring receivers are 1.300" or so and large ring are 1.400" or there abouts.

I ran the calcs on it back when I was in engineering graduate school but don't remember the details and have no desire do dig through books to prove it. Maybe a current ME or CE student can show the actual numbers if they are reading this.

The smaller cross sectional area of the receiver ring causes the stress seen by the ring to dramatically increase compared to the large ring actions, as Stress is Force divided by Area. The stress is high enough to exceed the metal’s ability to hold, leading to eventual failure. Well, of course not every rifle has problems after X number of rounds-depends on how many rounds and how high the pressure, plus which way the wind is blowing. When you are dealing with fatigue, there is so much scatter in the data that it is impossible to give a close estimate of how many rounds will be required to cause failure. It is just the nature of the beast. The small barrel shank has enough cross sectional area to be able to gold up. Also remember that the metallurgy in the barrel is different than in the action of the SR/LS Mausers, further increasing the small barrel shank’s ability to hold up to the stress of firing.

The rupturestrength of the 3 actiontypes in the length direction, calculated with strength data of low carbonsteel, with no significant heattreatment.
Smallring large tread 8.77 ton
smallring small tread 13.94 ton
largering large tread 14.87 ton

I have seen 1 smallring large tread who had ruptured totaly, throwing the barrel. I also have seen 4 smallring large tread with clearly visible stretching in the front of the reciever.

With standard casediameter, the smalltread shank is hardly the problem conserning radial spliting, compared to axial stretching of an low carbon reciever

With a case head failure the small ring may
blow out over the locking lug. The metal in
that position is about as thick as a razor blade.
The 03 Springfield is a copy of the small ring
Mausewr but you will see metal added there.
Good luck!

Another thing not mentioned is the fact that many of the earlier WW1 SR/LT receivers appear to be noticably softer than their LR/LT replacements, thereby contributing to the action's tendency to stretch. This perceived softness in some of the WW1 production may be due to the thinner ring rather than softness but the result is the same, these actions have a rep for being weaker than the others.
Regards, Joe

Don't forget; In the case of a modern small ring action with square bridges the front bridge adds metal along the top of the front ring. This adds more cross section to calculate.

Round actions are simpler in getting this cross section calulation.

M-98 and the other non-round actions have more area to calculate.

Modern receivers in 4140 will handle the higher pressure rounds long term.

We recently tested a modern 4140 1.300 diameter reciever,square bridge .980 X 12 tpi.
375 H&H: An honest bolt face thrust producer.
To Proof: 30% overpressure
No problem.
www.satterleearms.com

Thanks for the responses.
You learn new stuff all of the time.

David

I have heard the same thing. The difference is because the large threads supposedly render the receiver ring too frail for the higher pressures. But I do not know if this is indeed the case!

Small ring/large thread receivers stretch between the locking lugs of the receiver and the threads for the barrel, then they rupture. It is due to just not enough receiver metal to hold the barrel and bolt together - it's not the radial forces acting on the diameter as much as it is the linear forces pushing the bolt and barrel apart that the receiver must be able to withstand..

quote:

Originally posted by CMcDermott:
Small ring/large thread receivers stretch between the locking lugs of the receiver and the threads for the barrel, then they rupture. It is due to just not enough receiver metal to hold the barrel and bolt together - it's not the radial forces acting on the diameter as much as it is the linear forces pushing the bolt and barrel apart that the receiver must be able to withstand..

Some do, that is correct. Some are much less prone to this and thus more suitable as a basis upon which to build a custom rifle.