Interesting information provided here by Michael Petrov and Mauser98.

Clearly Paul Mauser intended the so-called "thumb notch" to be a safety modification designed to divert escaped gases from a ruptured cartridge case.

By all credible accounts, it seems to work as intended.

The right thumb, which for most is the thumb of the strong hand, is the one Mauser recommended for use, and apparently the one generally used, for stripping rounds into the magazine box from a stripper clip.

So, no need for a thumb notch for loading purposes. Although some report that it is useful for lefties and for loading single rounds into the magazines of heavy caliber rifles. Unintended beneficial consequences, it seems.

As far as the original design intent is concerned, however, calling this slot a "thumb notch" would, in fact, appear to be a complete misnomer.

Thanks to Michael and Mauser, I have learned my daily ration of gun knowledge.

The M98 began primarily as a battlefield rifle.
IN battle people get injured/incapacitated to different degree.

IF ones right hand/arm/shoulder was injured to some degree,
one may find themselves needing to use ones LH to do [or assist] in things you would normally do
with ones RH.

I am also confident the debilitating cold of the severe Russian winter,
had some German soldiers regularly using both hands[including left thumb] to help insert clipper strips.

Hence the gas slot would have been helpful for soldiers needing to adapt to those battlefield scenarios.

Having said that,
Germanies advanced WW2 automatic assault weapons that accepted the M98 clipper strip,
did not feature a gas slot/come 'thumb notch', like the M98.

We seen many custom M98 rifles that have M70 type 3 pos.safeties,
Yet I dont see custom M70 rifles that have had an M98 style 'thumb notch' added.

Why would that be?

I can't think of any modern post-war commmercial Mausers with thumb cuts: FN Deluxe/Supreme, Mark X, Brevex, Prechtl, Granite Mountain, Vektor, Brno, CZ, etc, etc, not to mention all the Mauser derivatives.

quote:

Originally posted by Trax:
We seen many custom M98 rifles that have M70 type 3 pos.safeties,
Yet I dont see custom M70 rifles that have had an M98 style 'thumb notch' added.

Why would that be?

The M70's lack of a guide rib would make the left lug likely to jump the raceway causing a jam.

Finn Aagaard wrote that his partner filed a thumb notch in one of his M-70 rifles but didn't like it and said he would never do it again.

I filed on into my MK X and personally find it an improvement for quickly stuffing more ammo in.

quote:

Originally posted by N E 450 No2:
The purpose of the thumb notch was to aid in loading a combat rifle with stripper clips.

For a sporting rifle the thumb notch is not needed.

My 9.3x62 Husqvarna has the thumb notch and stripper clip cut. I carry my spare ammo in stripper clips so there's a good reason for these features to exist. Also if you reload like Bell you'll use the thumb notch to press the round into the magazine with your left thumb while you pull another round out of your ammo belt with the right hand.

But I agree with wondering why you would want to eliminate the thumb cut if it was already there.

quote:

Originally posted by 458Win:
Finn Aagaard wrote that his partner filed a thumb notch in one of his M-70 rifles but didn't like it and said he would never do it again.

I filed on into my MK X and personally find it an improvement for quickly stuffing more ammo in.

Phil
I know that you and Finn were close so I don't want to contradict you but I believe Finn stated that it was Nicky Blunt(not Finn's partner) who filed the notch in a M70. Finn went on to say that he would not have done the alteration himself due to the lack of a guide rib and the problems that would cause.

I am often wrong, but I went back and re-read Finn's article "Make Mine a Mauser".

Finn is, and forever will be, my hero and mentor. I still sorry that I never took the time to tell him that.

quote:

...Also if you reload like Bell you'll use the thumb notch to press the round into the magazine with your left thumb while you pull another round out of your ammo belt with the right hand.

Excellent point.
Also, with many Mausers, it is away of pressing the full load of cartridges down into the magazine and closing the bolt over them on an empty chamber or enabling one to go up the spout over a full magazine.

Just for the record, here is a pre-War Oberndorf Magnum action without the thumb notch, but with the Springfield/Enfield/Model 70 relief cut at the top of the left wall:

The 1901-2 Springfield did have a large notch in the left side and was dropped by finial development of the 1903. I suspect (but don't know) that Springfield thought it was also for loading until Mauser informed them what it was for and pointed out their patent.








Also please remember that the 98 bolt has a gas port both in front of and back of the extractor collar that lines up with the left rail when the bolt is in battery. Might not be a good idea to close off the notch (even with wood) because any gas that enters the bolt body will exhaust in the left rail.

Here, from Britain, is my 2c worth:

The thumb cut may be useful for loading but I have, in my time, loaded enough Lee-Enfield rifles with a stripper clip to know that a thumb CUT (as Mauser) isn't needed just an area for the TIP of the thumb to travers down on the INSIDE of the left wall.

I've also loaded far less, but enough, military Mauser rifles with a stripper clip to know that when you do the thumb doesn't actually intrude OVER the thumb cut area. That is it doesn't stick out past the left edge of the left receiver wall.

Indeed if it does you are applying less efficiently the downward force with your left thumb as it means it is wrongly positioned! LOOK AT THE DIAGRAM - WHERE IS THE TIP "AREA" OF THE THUMB? ON TOP OF THE ROUNDS!

To my mind the lack of a thumb cut on MODERN MADE Mauser type actions is based on two sole reasons:

1) If it has a thumb cut if falls foul of BATF regulations even if it is not actually an ex-military action. So those wishing to sell into the USA simply omit it as it avoids any argument that it is or is not an ex-military action.

2) Cost! It is cheaper to make it WITHOUT the thumb cut just as...cost again...it is cheaper to machine a Mauser action as a H type recess at the loacking lugs rather than as on the original design a C type recess at the locking lugs.

So for what it's worth IMHO it is 2) that NOW dictates why modern made Mauser actiosn don't have the thumb cut off....or the C type locking lugs recess.

quote:

Originally posted by swarf:
Somewhere I remember a picture of an old Model 70 target rifle by Roy Dunlap where he had proudly added an M98 type flange to the bolt shroud. Probably just soldiered on.

Anyone remeber the article and or picture? Come on you other old guys. I'd love to look at it again.

I don't have the article or the pictures, but I do have pictures of a Dunlap gas shield on a target rifle which once belonged to me:

The thumb notch, was not introduced on the m98.
Pretty strange it was patented in 95, but it was used on the m94 versions.
Funny how a discussion, can go on for days, with that little facts, and that little real knowledge about what actually happens, when "shit happens"
The thumb cut, is basically of relevans when using stripperclips. On larger cases, it is of no relevans. It would not give you any advantages, when loading cartridges 1 at a time. You can as well use your nr 2 and 3 fingers on your left hand aiding reloading, as you can use your left hand thumb.

The m98 is upgraded on gashandeling, according to earlier mauserdesigns, by adding shields on a basically poor gashandeling design.

Savage and fatbolt designs is far supirior in gashandeling.

The thumbnotch leaves you with an action as stiff as a young willow, completly rubish for scopemounting

quote:

Originally posted by jørgen:

Funny how a discussion, can go on for days, with that little facts, and that little real knowledge about what actually happens, when "shit happens"

That is why I asked you to weigh in, I know you have extensive experience with destructive testing on actions.

We have went around and around on the reason the "thumb notch" was utilized. The original patent stated that it was a gas handling feature.

So, ignoring its use when loading, I ask you:
In your opinion(and/or according to the results of your testing) does the "thumb notch"

A)-enhance gas handling in the event of a case failure....

and alternately

B)-does the gas that is vented through the thumbnotch actually endanger the shooter by venting gas towards their face/eye?

@ Jason

There is no precise answer to that question.
To a certain degre, it reduces the volume/presure of gas reaching the boltscrout.
On limited gasleaks it might help a little. On masiv leaks,it gives in some shootingpositions, especialy with scopes, free acces to parts of your face/left eye.
Typically, if large leaks, the boltstop is blown out to the side,and often the boltstopspring is broken of and blown back werry close to your face. That happens even with the thumbcut, so actually the effect is rather limmited.

According to several tests i have performed, a CRF rifle, in a standard caliber, blows fatally at 50%-70% of what presure is needed, to blow a PF rifle with a Sakotype extracter, and at less than 50% of what is required to blow a Remmington type.
When there is massive casehead leaks, it often increase the thrust on the bolt by more than 100%, because of increased presureares.
Mauseractions that we blew at a presure, where modern PF rifles was easily opened by your fingertips, was totaly destroyed, with loss of extractor, boltlugs, and a rupture of the action in the thumbcut.


I might sound werry negative on the mauseractions, that is not the fact. It is as safe as most other designs, with raceways.(savage has a superior solution)
What makes me provokate a little, is all the statements trying to give it a Gods status. Primarily based on hersayes, outdated articles and rumors.

According to CRF, it is as Darcy D'ecole wrote, werry dificult to trimm to perfection. Often it is badly adjusted, and therfor not a bit more reliable than most PF.
If a design requires a lot of individual twiking and trimming to function reliably, is it then a superior design?????

quote:

Originally posted by jørgen:

When there is massive casehead leaks, it often increase the thrust on the bolt by more than 100%, because of increased presureares .

Thanks for that honest assessment. I believe you meant the bolt thrust increases because of increased "surface area" rather than increased "pressure". I recall the first time I read your explanation of the increased bolt thrust during a case failure due to the pressure being exerted against the ENTIRE boltface instead of only the inside rear of the case: suddenly it all make sense to me!

I will continue to shoot Mausers because I like them, not because I believe they are stronger than other actions. Having said that, I am very careful about the loads I shoot.

It seems that casehead failures are very rare and those that do occur are due to gross negligence(shooting loads far above safe levels, using incorrect ammo, etc.)

Sorry Jason for my bad spelling an grammar.
I dont speak or write english on a daily bases.

I actually wrote what you understood. Presureares, i shoud take a course i spelling , as it should have been "presure-areas"

About the frequense and cause of blowups, i belive you ar pretty right.

quote:

Originally posted by jørgen:
According to CRF, it is as Darcy D'ecole wrote, werry dificult to trimm to perfection. Often it is badly adjusted, and therfor not a bit more reliable than most PF.
If a design requires a lot of individual twiking and trimming to function reliably, is it then a superior design?????

The mauser is indeed superior in some functions...thankfully some intelligent capable individuals know how to tweak & adjust it,
- in order to get the best out of it.
kind of glad some innovative & technically capable people still tweak the mechanical watch movement to make it function reliably.

When an M98 fails [under extreme circumstances], it does not always hold-Up [or Fail], in the areas one might typically imagine.


>> http://www.yarlooprc.com/Artic...8%20Blow%20Up/18.jpg

>> http://www.yarlooprc.com/Artic...98%20Blow%20Up/6.jpg

- Third lug wont save you b-cause the action has completely lost its rear-enD.
- Solid left wall broke in same region that a weaker 'thumb-slot' featured M98 typically might.

Tom Burgess noted that H-ring fnM98,[in extreme overload], split open all way along the left wall up to the extractor slot.

note: Mr.P Mauser designed the M98 to help better handle a ruptured case scenario ,on military issue ammunition.
not ridiculous insane overloads by todays negligent backyard handloaders.

Not many,if any, BA action design, will handle that kind of individually extreme human negligence & stupidity.

The technically amazing& advanced passive/active safety,handling,performance & design features of todays Porsches (vs) those of decades past,
..dont even compare.
However if I negligently put that current Porsche into a pole or wall at high Speed,..I am still dead as a door nail.

There is an awful lot of confabulation here by people that have never seen anyone gassed by a 98, never been gassed by anything themselves or have never tried lot load a Mauser in freezing weather with heavy gloves.
I like the notch because it aids loading and does everytime I load one away from a bench.

To believe it is a gas vent is fantasy regardless of what someone wrote in Mauser's patent application. He was a good designer but don't bet your life on how good he was at hiring people to write patent applications. You see the one pasted earlier, what you may not see is many others that might have been turned down. Einstein commented about his time as a patent examiner. He examined many patents that he rejected because they clearly were bogus and could not work. So Mauser's thumb cut was a vent - yeah? Was it clearly safe?

quote:

Originally posted by SR4759:
There is an awful lot of confabulation here by people that have never seen anyone gassed by a 98, never been gassed by anything themselves or have never tried lot load a Mauser in freezing weather with heavy gloves.
I like the notch because it aids loading and does everytime I load one away from a bench.

To believe it is a gas vent is fantasy regardless of what someone wrote in Mauser's patent application. He was a good designer but don't bet your life on how good he was at hiring people to write patent applications. You see the one pasted earlier, what you may not see is many others that might have been turned down. Einstein commented about his time as a patent examiner. He examined many patents that he rejected because they clearly were bogus and could not work. So Mauser's thumb cut was a vent - yeah? Was it clearly safe?

Amazing.

So Mauser, who made a pretty penny off of the US government in royalties on the Springfield - until WWI interfered with his income - didn't know how to write a patent application?

I think not.