The Mauser K98 S (Spring) by M&G

A true Mauser

The Mauser K98 is an iconic weapon, a lot has been written about it and we'll not go there here.
What is important is that Mayer & Grammelspacher (makers of DIANA airguns) now belongs to the same industrial group that owns Mauser (among other prestigious brands), so M&G/DIANA can, in all honesty, make and market an airgun under the Mauser brand.​

The first time this happened was with the launch of the AM-03, an airgun version of a current Mauser sporting rifle.
We have already reviewed and commented on that one, so we will also skip that.

The second time it happened was when M&G decided to make a "facsimile" of the venerable K98 using the D460 Magnum as a platform/chassis.
The 460, being a svelte and powerful lady made a lot of sense as a spring-piston version of the war horse that is the K98.
There is another version still, as a PCP, but we will tackle that at a later date, as it has much in common with the Stormrider and we have explored that one fairly in depth.

So, what we are looking at in detail today is this:

Nice! ¿No?

Well, a few "pundits" have complained that  (insert Gilbert Godffrey's voice here:) "it lacks a bolt".

Ok, so, this is the difference between a replica and a facsimile.

Replicas are supposed to be identical to the object they replicate (am I making sense here?) .

The word "facsimile" comes from the Latin "facia" and "similes", which means "similar face".
In a DOCUMENT, a facsimile is an identical copy because a document is nothing but a "face", in more bodily goods, a facsimile is understood as being "similar enough" , but not necessarily identical all around.

So, having clarified that, perhaps we also need to say that the idea had been brewing for a number of years.
​Back in 2018, at the IWA, DIANA showed this:

That year, we had good, long, conversations with my friends Michael Swoboda and Florian Hassler, CEO's of M&G who are great fans of history and finely made guns so, this model holds a special place.
In here, I have to say that Florian will be retiring from DIANA/M&G at this year's end and that, personally, I will miss him much. We may have not always agreed on technical stuff, but the respect and gentlemanly conduct of the person made him very dear to me.
Back to the k98: the model was produced for a few years and, due to economic conditions, is now out of the catalog; at least for the foreseeable future, but there are enough around that they merit a study in depth.

A project is born

Back in November of 2020 (yes, that is a long time ago), a friend asked me a BUNCH of questions about the K98 S (for spring), and they were dutifully answered. Little did I know that it would "unchain" a series of events that would take years to consolidate into a solid idea.
First of all, my knowledge about the different models and issues of the k98 was somewhat sparse.
AaMoF, even the "experts" could not agree on certain aspects, like which scope, how it was mounted, how did the stripper clips fit into the picture, was the "grunt issue" buttplate always in place, what other modifications were done, etc, etc, etc....

As my enquiries progressed, two notable companies with whom I do some small, but interesting business, started asking ME questions!?!?!?
Wait, what? I am the one that asks the questions here,  LOL!

It ended up that they came up with VERY interesting replicas (now these are TRUE replicas) for parts that are extremely scarce, and yet highly sought after. Now the powderburners have access to replicas of parts that might enable them to build a SS K98 using old actions/basic guns available in the surplus market, into something historically accurate and functional.
BTW, there are matches that are limited to originals or true replicas, and very few will enlist a $24k gun into a match, LOL!

We'll come to that in a moment.

The other thing that happened, was CoViD. Yes, the world stopped for almost two years. And it took one more year to get all the delayed stuff over!

Once everything was sort of back on track, we could take up the project again.

In here, I have to extend to my friend/customer my heartfelt gratitude for his patience and understanding.

​So, where does one start?

"In the beginning"

Famous words from one of the most read books. But, back to airguns:
​
In the beginning there was an idea:
To turn the k98 S into a shootable/enjoyable/accurate/easy to shoot machine; while respecting the "spirit" of the beast and its specific incarnation as a Sniper's Tool (ScharfSchutzen Gewehr-SSG)

Most of us are fairly conversant with the two main "embodiments" of these:
​
The small, forward mounted scope:

And the quick detachable "high mount" that offered the opportunity to use the iron sights on the fly:

When developing these ideas, there is no alternative but to get, physically, the parts you need, or believe you will need and "try them on for size".

So, in this way I came about getting this:

Yup! My good friends at Vector Optics made a run of replica mounts for the 98k. And I mean replica.
They allow the use of the iron sights:

The mounts are "claw" style in the sense that there are "tabs"  that secure the front mount:

Then the whole assembly gets inserted:

And rotated:

So that the "claw" at the rear slides in and catches

And the mount gets locked by turning the rear lever to the back:

There is absolutely no doubt about the strength of this arrangement, and it incorporates windage adjustments:

The scopes themselves had the elevation turrets.
​
As much as I like this system, we could not use it and still keep the "scope forward" mounting version.
MOSTLY because the D460 is loaded exactly at the point where the original forward mounted scope would be.
There is nothing as displeasing as an airgun that is hard to load.

The last thing to mention that is interesting for us, airgunners, is that the mounts allow for "droop mount" compensation:

If you are wondering why mount the parts into wooden "dummies", it is because these parts are made to VERY TIGHT tolerances, and so, you need to "work them well" BEFORE installing.
You do NOT want your scope to be the lever that "loosens up" the mounts.
The curvature of the mounts follows VERY closely the curvature of the mechanisms tube in the D460, so soldering the mounts would have presented no serious trouble.

I MAY use these mounts in another specimen that will be upcoming. But, for THIS specific version, where the user wanted a "forward mounted" scope, we ended up having to use a "reversed" version of the Hawke adjustable dovetail to weaver rail with extension.

​The OEM part starts like this:

But it is designed so that the extension protrudes to the REAR, if you see in the picture above the "hinge" is located on the opposite side to the extended part of the rail.
So, the reversal starts with changing the arrangement, and because we wanted no "slop" we started by turning a brass pin to replace the loose hinge pin in the OEM piece:

We had to relocate the droop adjustment screw and the locking screw:

And then the rail could work as we wanted:

Do note that the k-98 S's loading port is "clear" of the scope's bell and loading is not a problem.

Not bad, ¿huh?

The other part that came from a totally unexpected source was the "Geriffelt Schaftkappe". One of my main peeves about the K98 S's (and I've sold a few) is that, for precision shooting, the smooth buttplate simply does not "cut it". It slips at the worst possible moment. 
I always wondered how the snipers of the time adjusted to that, and I found pictures of a number of rifles wrapped in rags, others with filed marks, and still others that had actually received a "grooved" (geriffelt) buttplate (Schaftkappe).
​
​So, when I received this from my friends at ADE:

I was very pleasantly surprised.

​The difference is day/night:

Now, you MAY think that the replacement isn't a direct one because the stock screws do not align, but the reality is that the stock-maker actually replicated the stock's rear, and the stock DOES have a screw hole in the right place.
​These butt-plates are VERY strong pieces (after all, the butt was part of a war implement) that are like a "cuff", meaning that they go OVER a "reduced" section of the stock. I was somewhat fearful that the reduction would be different in the Mauser by DIANA stock vs. the original Mauser version, but lo and behold! Perfect fit!

With the addition of a leather cheekpiece, combined with the very low rings and small scope, the rifle can be used with both, iron and scope sights.
The leather cheekpiece can be available in RH or LH version and you can cut slots in the "off side" to allow the two part Mauser K98 sling to be used.

The rail and the scope rings do not allow the simultaneous use of the iron sights and the scope, but by removing the scope WITH the rings, the iron sights are clearly usable:

A quick walk-through of the ergonomics showed that we had achieved the objectives:

Looking through the scope was an interesting experience, at 2X it offers a wide field of view:

At 7X it affords quite a lot of detail:

So, now that we had the "dress" it was important to get a performance that honored the likeness.

The Powerplant

The idea was to have a 13 ft-lbs springer that could be shot all day without too much fatigue.
So, initially, I had thought about using a short stroke piston:

AND the output was there. BUT the cocking stroke could not be altered in such a way as to reduce the PCF (Peak Cocking Force).
Exerting 45 # F, even for a short arc still requires the human to exert the force, and humans fatigue on the force exerted, not the total energy input.
So, building on the work previously done in the LGU Ultra Light (UL) Piston, we devised one for the D460.

We used a Titan #1 spring, with one coil lopped off.
In here an important note:
The "NEW" Titan #1 is not the one we had come to love. And I cannot but blame our European "cousins" that complained endlessly about the #1 not being a "standard power" spring and being "too powerful and not a drop-in for 12 ft-lbs". The "NEW" #1 is a good 0.010" larger in OD, and  0.002" smaller in Wire Diameter.
And those differences are important, just plug the numbers in a spring rate calculator.
The other aspect is that the ends of the spring are not forged parallel.
The ends are somewhat "conical". The last coil or coil and a half are substantially smaller than the ID of the rest of the spring (0.583" vs. 0.624"), so that created a huge headache. We ended up "opening up" the ends.

And had to turn two different guides.

Anyway, by using an UL piston, we could "tune" the shot cycle to the power we wanted and the pellet the barrel preferred by modifying the weight of the top-hat alone, while keeping the PCF to 31 # F.

Extensive tests in a D52 platform yielded interesting results and by the time we settled on an arrangement, the whole was transplanted into the k98 S.
Results were a bit on the low side to start with:
JSB Xact .- 11.6 ft-lbs
H&N B-8.- 12 ft-lbs
QYS SL.- 12.1 ft-lbs

So we changed the top hat to a heavier one:
JSB Xact.- 12.9 ft-lbs
QYS SL.- 13.2 ft-lbs
H&N B-8.- 13.2 ft-lbs

BINGO!

The lowest spread was obtained with QYS SL's, but those pellets are not easy to obtain, so we did the rest of the tuning with the H&N B-8's

In the end, after about 500 shots the gun was yielding 838 ± 4 fps with the H&N B-8 that are 8.44 grs. (nominal).

The process

We'll be tacking here the K98 S serial # 25030667, which should be fairly typical of all others.
To disassemble a Mauser K98 S you will need some special tools.
DIANA includes them in the box, so if you got your gun second hand, you may not get them.
One tool is for adjusting the front sight's elevation; the other, the most important one is a 3 mm's thick 16 mm's wrench.
​You can make one from a bicycle wrench in 5/8" if it does not happen that the tolerances in these cheap tools allow dual usage.

The notches are to allow the use of this tool also for tightening/loosening the scope rings.
​
You need to remove the muzzle piece:

There is a tiny retaining screw at the top, behind the sight blade that needs loosening. Do NOT forget this!

The tiny screw at the FRONT of the front sight base is to set the blade. The blade gives you a wide range of vertical positions by screwing in and out the whole blade.

Do note there is a flat at the bottom and the piece will always align properly. Just do not force it.

Once that is done, then the "train" can start coming out. Open the lever:

And using a shaped block, tap to remove the front metal guard:

This will allow you to slide out the first "wagon":

Now, keep that part as an assembly:

And note that there are small pins and big pins. You CANNOT assemble the part in the wrong orientation if you follow those. Now remove the second metal part and put it in the train:

You will now need to disassemble the stock from the action because there is one piece that is "keyed".
​
Loosen the fore end screws and the rear stock screw (front trigger guard screw):

Check the screw wells for damage by the star washers:

Clean it up

You will need to reinforce that with some steel flat washers. That will be done later.
Remove the rear stock screw and now take the action out of the stock:

Now you can slide the top wooden piece out of the barrel:

If you look at that part from the front, you will see how it is "keyed":

And now you can put together the whole "train".
Keep it all together in a box, old scope boxes work very well for this:

Now you have a D460 action you can work on:

On of my favourite parts:
​
​"Look Ma!, it's a genuine Mauser"!

Put the action in the compressor, replace the action pins with the dumb pins, open the action and remove the power plant:

The cocking lever arrangement is disconnected:

And the lever linkage is disconnected from the compression chamber:

Once the compression chamber is extracted, the breech seal can come out:

To my surprise, a spacing washer came out.
We had to turn a special reinforcing insert and replace the seal with a new one:

The barrel was cleaned:

And the inside of the mechanisms tube was de-burred / polished:

Now the barrel work can start.
As it has become somewhat "normal" for DIANA airguns in 0.177" cal., the barrel's leade was too lose for the precision pellets we normally shoot (JSB, H&N, QYS), so that leade needs to be shortened.
Because the 460 has an offset barrel in relation to the compression chamber, we needed to make a special tool:

The brass pilot was turned to the diameter of the chamber (that differs from the diameter of the barrel at the choke). The tool also needed to connect to a manual drill and extensions:

To reach deep into the D460 action:

We made sure everything was square:

And removed about 0.5 mm's:

Once that was done, we performed the trigger work and affixed the external retaining rings we use in all our builds:

The powerplant was changed and upon assembly, we took care of the screw wells by gluing flat washers at the bottom:

And replacing the star washers with Nord-Loc washers:

The assembly went in reverse order EXCEPT for the addition of barrel shims between the barrel and the barrel sleeves.
This is a part hat DIANA uses in ALL the rifles under the 48 -> 56 model numbers, so I do not know why they excluded it in this model that, because it has so many "thingies" hanging out there, needs it the most.
Shims were cut from larger stock and sized precisely to the lengths needed:

To cut thin materials, you need to use a mandrel:

Now we have a superb fit:

ORings added:

And a magnet glued to the spot where the lever needs to be held.
If the gun is disassembled, then upon assembly, care needs to be taken to align this magnet with the cocking lever to make this secure.

The results

Now, was all this work worth it?

I would answer with a resounding yes.

I took advantage of an outing to the WAC-DIFTA airgun range to test it at distance.
And, on, purpose, did not take any other rifle apart from this one.

For starters, it is truly a beautiful lady, and once I became somewhat familiar with the 7x scope and the duplex reticle (a FAR cry from the 30X Xmas tree style I normally use), this Valkyrie (war lady) allowed for a more than reasonable performance.
Targets were set at 10, 25, 40 and 55 yards; on one hand to reflect the distances that the Pyramyd Air Cup "Gunslynger" silhouette style shoot is shot at, and on another, the max distances allowed in WFTF for targets of 15, 25 and 40 mm's diameter.

The FT targets were for my friend Toby, that is starting his FT career

I am still hopeful I can convert him into a Spring-piston shooter, LOL!
The silhouettes were mainly for the K98.
The first round of 20 shots, was taken to decide HOW to sight in the rifle:
​The chicken:

The Javelina (wind started picking up):

The Turkey (I started paying attention to the wind):

And the Ram.
​I had no idea where the shots were going to land, but the fact that all the shots are in a horizontal line told me the pellets were being stable at this distance, and that was a huge success:

After retrieving the targets and taking some measurements, I decided to sight-in the rifle with the crosshairs, dead on at 25 yards and holding off for range and wind.
These are the results, do note it is a 7x scope, LOL!

​The chicken:

5 hits, now the javelina:

Another 5 hits and still refining the POA's, now the turkey:

At this distance, the hits are no longer visible through the scope still, not bad, 3 hits on the hardest target in the silhouette game from a 7X scope. Not too shabby, at all.
Now the ram:

Aaaarrghhh! The wind got me.
The ram was located above all the other targets, so more open to the wind.
Still, not bad.

Would I be competitive in a current Gusnlynger?
Nope! LOL!

It is a young man's game now. I shot 20 "for score" shots in 2:45 with 3 misses

The current youngsters shoot all 20 targets down in 1:30

:-(  LOL!

Still, it was a wonderful experience shooting the K98 S SSG at extended distances.

It COULD be a good gun for Hunter-Piston under AAFTA rules, perhaps shooting a bit "hotter", something that this platform is perfectly capable of doing. The 55 yards "group" printed on the Ram measures 30 mm's c-c, or 35 mm's O-O, so they would all have gone into the 40 mm's kill zone, given correct wind reading, a better scope (up to 16X allowed under the rules) and, most importantly, a better shooter, ROFL!

There are several factors for the accuracy and precision of the K98 S SSG in this tune:
1.- It is a heavy rifle; 10 # with a small scope
2.- Barrel is tensioned
3.- The shot cycle is extremely fast, it is not even a "thump", it is more like a dry "TK"
4.- The rifle proved to be hold insensitive.

There are still some of these rifles around that are available, if you are in the market for an interesting piece of history that is, at the same time enjoyable and useful (could be a great hunter in 0.22"), then look into it.

Thanks for reading!

Keep well and shoot straight!





HM​