Mondragon M1908 Mauser
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Mondragon M1908 Mauser

Peter C. Schechter

Whether selling or buying a gun, doing so by the auction process has both risks and rewards. There is also the possibility of surprises, sometimes bad and other times good. This is a story of a recent rewarding purchase with good surprises.

The result is that I now have an example of both of the semiautomatic rifles used by opposing World War I British and German airborne fighters in the first-ever aerial combat conducted with weapons other than side arms. That sort of air-to-air combat was short-lived, though, because the Germans figured out how to mount a forward-facing Parabellum machine gun on a Fokker Eindecker in mid-1915.

In my previous TTAG article called “The Dawn of Aerial Combat,” I wrote about one of the only two known surviving examples of the Winchester Model 1907 S.L. (Self Loading) rifle as modified by the British Royal Flying Corps (RFC) for air service.

Mondragon M1908 Mauser

In a nutshell, by late 1914, the Brits needed some form of armament to respond to their observation plane aircrews being shot at by German fliers equipped with modified Mexican Mondragón M1908 7mm Mauser semiautomatic rifles later designated by the Imperial German Flying Corps as the Fl.S.K. 15 (Flieger-Selbstladekarabiner, Modell 1915 – Aviator’s Selfloading Carbine, Model 1915).

A decade earlier, Mexican General Manuel Mondragón filed an application for a United States patent on a new and improved (over his own previous designs) semiautomatic rifle, and was granted U.S. Patent Number 853,715 on May 14, 1907. The patented design was adopted by the Mexican Army in 1908 as Fusil Porfirio Díaz Sistema Mondragón Modelo 1908 (M1908).

Because no Mexican firearms manufacturer could produce Mondragón’s rifle at that time, Mexico contracted with the Swiss company Schweizerische Industrie Gesellschaft (better known as SIG) located in Neuhausen, Switzerland for production of four thousand M1908 rifles.

By 1910 only about 400 rifles had been delivered by SIG to Mexico. While the Mondragón M1908 became the first ever semiautomatic battle rifle issued in significant numbers to regular infantry troops, the Mexican Army nonetheless did not like what they had ordered and received. The rifle’s inability to cope with poor quality Mexican-made 7x57mm Mauser ammunition, and its intolerance for sandy environments, plus the high per-rifle cost charged by SIG, led the Mexican government in 1910 to cancel the remainder of the order.

The Fusil Porfirio Díaz Sistema Mondragón Modelo 1908 (M1908) is likely “the most important gun you’ve never heard of.

That left SIG with an inventory of several thousand undelivered Mondragón M1908 rifles in various states of assembly. It seems most likely that the inventory and production machine tools were mothballed at that time.

When the First World War broke out across Europe, the Imperial German Army learned of SIG’s undelivered inventory of as many as 3,600 Mondragón M1908 semiautomatic rifles. The rifles were tested by the Germans for infantry use, but were found to be intolerant of trench mud and dirt and their use by German infantry troops was rejected.

The Germans figured out another use for the dirt-intolerant rifles, however, and bought all or nearly all of SIG’s Neuhausen’s inventory with the intention of modifying them for use by aircrews in observation aircraft flying over the battlefields of Europe. The result was the German Fl.S.K. 15.

Mondragon M1908 Mauser

Despite its failings, the M1908 made by SIG was actually a great rifle. Had SIG’s engineers spent a little more time to make it function more reliably in dirty, sandy conditions, and tolerant of a wider range of ammunition quality, General Mondragón’s semiautomatic rifle may well have become the world’s main battle rifle for many decades.

The action’s design was well ahead of its time. It has a gas-operated cylinder and piston arrangement to drive the bolt carrier by way of an operating rod – startlingly similar to the gas operating system of the M1 Garand. It has a rotating bolt with forward-positioned locking lugs that engage helical lugs in the barrel block to go into battery – virtually copied by Eugene Stoner more than fifty years later.

Cleverly, the charging handle/bolt assembly could be instantly disengaged from the gas system, the rifle then operates as a straight-pull bolt action rifle. Conventional military doctrine at the time disfavored rapid-fire infantry rifles, as commanders believed that soldiers would simply “waste” ammunition if they could fire their weapons faster. Even the M1903 Springfield bolt action rifle had a switch preventing soldiers from reloading cartridges from the fixed box magazine with each cycle of the bolt handle.

While the M1908 had a non-detachable box magazine with ten-round capacity that was charged using two five-round stripper clips, the magazine box doubled as an integral magazine well for receiving removable high-capacity magazines, as the Germans proved, a feature not seen again in a battle rifle until Dieudonné Saive’s FAL design in the late 1940s (though it was seen in the intervening decades in a few machine guns and submachine guns).

The M1908 as designed and built for the Mexican Army was also equipped with an integral folding bipod and a unique multi-function bayonet (which is MUCH more rare than the rifle itself). As aptly put by the author of the information-packed website, the Fusil Porfirio Díaz Sistema Mondragón Modelo 1908 (M1908) is likely “the most important gun you’ve never heard of.”

I had always placed the Mexican Mondragón M1908 rifle (and any of its variants) in the “Unobtanium” category of my battle rifle collection. Precious few of them exist today, and when one does come on the market, usually at auction, it sells for upwards of at least $20,000 and ranging up into the mid-to-high five figures. That sort of collecting is The Sport of Kings, or at least of very rich folks, as far as I’m concerned, and I don’t fall into either group.

Recently, however, a previously unknown example of an Fl.S.K. 15 was offered by Rock Island Auction Company, one of the best-known auction houses for high end collectible guns and militaria. The pre-auction estimated price was uncharacteristically low because, it seemed, the gun had a few “issues.”

I figured that if I couldn’t ever own a pristine example, maybe owning a gun with issues was better than not ever owning one at all, especially if it was in my “affordable” range (albeit at the very top end of that range). And here’s where the story starts to get interesting, and when I learned a thing or two about auctions.

Now, I’m not a noob as far as buying and selling guns at auction is concerned. When I sell, I try to detail and photograph every conceivable fault I can think of and find so that no one ever accuses me of hiding anything. On the flip side, however, some of my best wins have been for guns where there was precious little information offered by the seller – few decent photos and even less in the way of description.

That lack of information discourages many potential bidders, in my experience, because you don’t really know exactly what you’re bidding on – you have to do whatever research you can, scrutinize whatever photos there are (or ask for more in a private message – a huge advantage if the seller is willing to provide any to you and you alone). Then you go with your gut instinct and place a fair bid.

A few times I’ve been disappointed and paid a little too much for what I got, but more than a few times, I got much more than I paid for and was very happy with the outcome.

Back to the Mondragón rifle. It was being offered in an RIA Premier Auction along with more than 2,300 lots. That’s a lot of guns needing to be photographed and described. The first and possibly most important lesson I learned in this case is: while RIA’s staff is excellent as a rule, knowledgeable about a huge range of firearms history and technology, and always does top notch work, they are still human beings and, well, “to err is human.”

If you can’t go to Illinois to attend the one-day auction preview/inspection, you need to realize that the written description of a particular gun — especially a rare one for which relatively little information is available — may not be entirely accurate. And as I said, that can be a bad thing or a good thing.

Moreover, the few photos included in the auction catalog may not give away any clues about the error. In this particular instance, the description contained multiple errors (unbeknownst to me at the time) that I believe worked in my favor by discouraging other potential bidders. The mistakes also probably mean that the consignor knew very little about the rifle. I would not be surprised if it was sold by a family member who found it after its owner had passed away.

To my great surprise and amazement, I bid and won the rifle for less than the high end of its very low pre-auction estimated price, and less than my authorized high bid as well. When I received the gun, completely mummified deep inside bubble wrap as is RIA’s customary excellent shipping practice, my journey of discovering exactly what I had bought began.

Here are some of the things that were stated in the RIA auction catalog that warranted investigation, and what I figured out about them.

(1) “Caliber/Gauge: 7mm Mondragon”

The short answer is, “wrong,” and not only because there is no such thing. While some of General Mondragón’s earlier prototype and experimental rifles were chambered for his own unique 6.5x52mm Mondragón small caliber high velocity cartridge, no Mondragón M1908 rifles were ever chambered for that 6.5mm Mondragón round. This rifle is chambered for standard 7x57mm Mauser ammunition, as ordered by Mexico.

This is what it shoots:

Mondragon M1908 Mauser

(2) “The rifle action is unmarked except for the serial number (1853) which is stamped on the left side of the action, top of the bolt, cocking handle and on the trigger guard housing directly behind the box magazine.”

There are “Swiss cross” acceptance marks on some parts of the rifle, and the serial number is also stamped on the barrel underneath the upper handguard. Also, nearly every metal part is stamped with a unique “heart in circle” mark, the origin and meaning of which remain unknown in the collecting world, except that it appears on nearly all examples of all versions of the Mondragón M1908 rifle.

Bearing in mind that all of the roughly 4,000 guns were originally produced by SIG Neuhausen under contract to the Mexican Government, I speculate that it is an acceptance mark of a Mexican arms inspector who was present at the Neuhausen Switzerland factory from 1908-1910.

Mondragon M1908 Mauser

Mondragon M1908 Mauser

(3) “Neither the magazine box, nor the buttstock are serial numbered (due to modification).”

Only the magazine well of the later Swiss M1917 modified version was ever numbered, so one would not expect the magazine box of this German Fl.S.K. 15 rifle to be numbered. And the stock of my rifle is in fact marked with the mysterious number 81.5, consistent with most or all of the German modified Fl.S.K. 15 rifles.

Mondragon M1908 Mauser

(4) “The rear receiver cap is an aluminum replacement that lacks any finish.”

This was the single biggest drawback of the rifle, at least as described by RIA, and was discouraging information, at best. A major component of the receiver was described as missing and replaced by what appeared to be a poorly executed replacement part.

And if the original rear receiver cap was missing, what other internal parts of the receiver or action might be missing? Does the gun even cycle? Here you see, side-by-side, the receiver cap on my rifle (on the right), and what the receiver cap should look like:

Mondragon M1908 Mauser

While the exteriors are obviously very different, upon quick examination I saw that the interior of the ugly part is identical to the interior of a correct receiver cap. Whoever made it had gone to great lengths to make it fully functional, or so it seemed, anyway. (I only have the one recoil buffer spring.)

Mondragon M1908 Mauser

The second important thing I discovered about the unusual receiver cap is that it is heavier than one would expect for an aluminum part. The third discovery was that it is strongly attracted to a magnet everywhere on the part. First conclusion: contrary to RIA’s description, it is not made of aluminum. But what metal is it then?

The fourth and fifth discoveries — after cleaning it up — were a Swiss cross acceptance stamp on the inside rear surface, and a faint “heart in circle” mark on the outside rear surface. Again, RIA’s statement that the “rifle action is unmarked except for …” was obviously wrong, though they could be forgiven for not cleaning the gun and then inspecting it with a good magnifying glass while preparing more than 2,300 lots for the auction.

Mondragon M1908 Mauser

Mondragon M1908 Mauser

I asked myself, is this really an original end cap with some kind of added metal on its outside? If so, what sort of metal is it, why was it added, and how was it applied without destroying the underlying original steel part?

I asked gun collecting experts, gunsmiths, metallurgists, and else anyone else I could think of. No one had any good answers that made sense. I considered having the part analyzed by X-Ray Fluorescence equipment to try to identify the added metal. I also thought about using ordinary weld inspection X-Ray imaging to look for a repaired or reinforced crack, but it was pointed out that even if it was steel weld material, it could not have been added without destroying the underlying steel part.

One solved mystery leads, however, to another set of unsolved, and probably unsolvable ones.

As I was taught in my engineering days, “if every answer that you can come up with is clearly wrong, you are trying to answer the wrong question.” Like a thunderbolt, it hit me: the right question that had to be answered is not “how was this extra ferrous metal added to the outside of the cap,” but, instead, “why was this surplus metal never removed from the outside of the cap in the first place?”

With that simple shift in thinking, everything was suddenly plain and obviously correct – the receiver cap is an original steel casting made by SIG Neuhausen in 1908-1910 that, for some unknown reason, was never cosmetically finished yet was still accepted as being entirely functional. The investment casting gas inclusions so apparent on the part’s surface — when you realize the part is “as cast” — make total sense.

One solved mystery leads, however, to another set of unsolved, and probably unsolvable ones: how and when did this raw unfinished component get onto the rifle in the first place, and how in the world did it survive on the rifle for 110 years?

There were a few other “issues” with the rifle as seen in the few photos in the RIA auction catalog, though nothing was said about them in the description. Only the most observant collector would have noticed. First, the bayonet lug was missing. At some point in the past, it was very carefully ground off. When and by whom and why is anyone’s guess:

Mondragon M1908 Mauser

Next, it appeared that the magazine catch added by the Germans to retain the 30-round drum magazine they had designed for the rifle was missing. In fact, it appeared that none of the German magazine modifications were present. But there was no indication in RIA’s description of what actually was present.

Upon close inspection of the actual rifle, while other German modifications to the rifle were made, it seems more likely than not that the magazine well was not ever modified to take the German Fl.S.K. 15’s drum magazine. The original Mexican Mondragón M1908 box magazine and all of its component parts (floorplate, spring, follower) are present and completely functional.

I’ll speculate about why this might be so in my conclusion to this article.

Mondragon M1908 Mauser

The slide part of the rear sight was also obviously incorrect although the ladder is the original part. This was explainable, at least in theory, by the fact that the slide stop screw that prevents the slide from sliding right off the ladder was missing, which at some point allowed the original slide to slide right off into oblivion.

I have replaced the incorrect part (seen on my finger, below) with a slide from a Mauser Model 1895 Mexican Rifle, which both looks like the correct part and would have been familiar to General Mondragón and the Mexican Army troops for whom the gun was designed. A slide stop screw has been added, as well, to prevent losing the slide again.

Mondragon M1908 Mauser

Finally, the rifle was not wearing a sling, and no one knows what sling it was originally issued with, if any. Milsurp rifles without slings look naked to me; I just can’t tolerate it. It stands to reason that there was a sling, though, because there are sling loops — unusually narrow sling loops, too narrow for a 1.25” wide sling.

One might think that because the guns were made by SIG at Neuhausen Switzerland, slings commonly found on Swiss rifles in the nineteen-aughts would be correct. SIG Neuhausen didn’t manufacture either the Schmidt-Rubin M1889 rifle or Schmidt-Rubin M1905 Cavalry Carbine, though, and had no reason to have any slings for any Schmidt-Rubin rifles on hand.

While SIG Neuhausen did produce several thousand Mannlicher M1893 Carbines, the sling for that rifle is just slightly too wide for the sling loops of the Mondragón M1908. So, I decided again to try to think like General Mondragón might have and, lo and behold, the 1-inch wide sling for the hugely successful Spanish Mauser M1898, which was the M1893 derivative that was then adopted by Imperial Germany as the Gewehr 98, fits the Mondragón M1908 perfectly.

Mondragon M1908 Mauser

Mondragon M1908 Mauser

At some other unknown time in the past, the buttstock was slightly altered by the well-executed addition of a higher comb section. Not at all well done, however, was the addition of the substitute crudely formed steel buttplate. That little restoration project awaits another day.

So, at the end of the day, as a gun collector all I really want to know is: what is the history of this particular rifle that I bought at auction? What incredible story would it tell if it could talk?

Here’s my best, though purely rank speculation at this point in my learning about the gun:

We know that when WW1 broke out, SIG Neuhausen had approximately 3600 unsold Mexican Mondragón M1908 rifles on hand, either complete or in unassembled parts. Imperial Germany bought most or all of them, trialed and rejected them as infantry weapons, and then decided to arm observation planes with modified guns later designated as the Fl.S.K. 15, two rifles per aircrew.

In June of 1915, German engineers successfully mounted a forward-facing Parabellum machine gun to the engine cowl of a Fokker Eindecker, thus instantly obsoleting the Fl.S.K. 15’s only wartime purpose. By that time, however, the entire fleet of the Fliegertruppen des deutschen Kaiserreiches consisted of only several hundred airplanes of all types.

Even assuming that each and every aircrew was issued two rifles, and that there were three aircrews for every single one of, say, 400 planes (and there were probably less than 300 even by the end of 1915), that’s still a total of only 2,400 issued Fl.S.K. 15 rifles. I’m not aware of any evidence suggesting, let alone proving, that every one of the roughly 3,600 rifles obtained from SIG was actually fully converted into a Fl.S.K. 15 gun and issued.

Thus, I speculate that Imperial Germany fully converted a sufficient number of Mondragón M1908s into Fl.S.K. 15 rifles and issued them as needed in late 1914 into mid-1915. They were in the process of converting more M1908 rifles when the Parabellum-armed Fokker Eindecker entered service in June 1915.

The roughly six-month Fokker Scourge followed when German planes ruled the skies over Europe’s battlefields. German armorers immediately stopped the M1908-to-Fl.S.K. 15 conversion project because it was suddenly a waste of time and effort, the Fl.S.K. 15 guns no longer having any actual operational purpose.

German conversion of my Mondragón M1908 S/N 1853 was already in progress in June 1915, I’d wager. The stock had been numbered upon receipt from SIG Neuhausen, the Mexican crest had been removed (assuming that it was present at all), the gas system selector switch lockout screw had been added after the proper hole was drilled and tapped, and the charging handle disengagement mechanism preventing the gun from accidentally switching from semiauto to single shot mode had been added.

But the conversion job wasn’t finished, leaving the original Mexican M1908 stripper clip-fed box magazine completely intact. The magazine well was never modified to accept the German drum magazine and the rifle was never fitted with the drum magazine retaining latch.

The additional fact that the gun has an original SIG-made, functional, though unfinished steel casting for its receiver end cap further suggests to me that this particular rifle was never issued to any WW1 aircrew; it wouldn’t have been the first gun in the pile chosen for conversion by me, had I been a German armorer in 1914.

There is so much to like about this gun and so much of it was a surprise learned only after I bid on and won it at auction, received and inspected and thought a lot about it. When you buy at auctions, you win some and you lose some, and hope it balances out in the end. This one was a big win for me.

I would be remiss if I did not express my deepest gratitude and sincere appreciation to the world’s foremost collector of Mondragón rifles, the publisher and author of the truly excellent website He helped me learn much of what I know about General Manuel Mondragón’s astonishingly innovative guns that were decades ahead of their time.

They had (in one version or another): a receiver with an integral magazine well; a high capacity removable magazine, a modular drop-in trigger assembly, an integral bipod, a gas-operated reloading system, and a 6-round en bloc clip using small caliber high-velocity ammunition (the 6.5x52mm Mondragón cartridge for the earlier Model 1900 experimental version). Not bad for that day and age.

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  1. Than you.

    I absolutely love reading material like this and learning about historic guns I did not know anything about. I wish I possessed your depth of knowledge. And, of course, your rifle 😉

  2. Thank you for the write-up…as Mr. Spock would say “fascinating”.

    Have you or will you ever fire it? Let us know how it shoots if you choose to test fire it.

    …and congrats on adding to your collection.

  3. Thanks. A very interesting rifle and article.

    I was also unaware of the Rifles used by the British. Learn something new every day.

    • Before WW1 there were many experimental self loading rifles. The Italians had the Cei-Rigotti, which was also tested by the British. The Danish had a Madsen self-loading rifle which progressed into the more well known light machine gun. During WW1 the Russians deployed the Fedorov rifle and the French had over a hundred thousand RSC 17 and RSC 18 rifles, which probably influenced the later US M1 Garand.

  4. Fascinating article in all aspects. Thank you. Had never heard of this rifle, nor it’s significance. One of the best TTAG articles I’ve ever read !

  5. How are you supposed to fit a red dot without a rail and it doesn’t take glock mags, ::Fail::.

    (Insert Sarcasm)

    • Yes, by all accounts difficult, at best. But easier and MUCH MORE EFFECTIVE with a semiautomatic rifle than with, say, a Luger P.08 or a Webley Mk IV or Mk V revolver, which is what the very first shots fired from flying machines were fired from.

  6. An excellent write-up on the Mondragon and a specific example of it, thank you for posting this.

    The early history of repeating arms from manual actions to the semi-automatic and automatic fascinates me for the myriad mechanical inventiveness of so many people. Some of these guns are complex puzzles, others are models of simplicity. That this history goes back at least 390 years to a lever action Wheelock and 135 years to a recoil operated, magazine fed semi-automatic is something too few POTG know.

    TTAG articles such as this are always enjoyable to read. Would enjoy reading a detailed review of all the semi-auto arms that emerged in the 1890 to 1920 period, in particular. It was a fascinating period of invention and advances with many of today’s modern firearms carrying forward concepts from a time that, once again, too few POTG are much aware of.

  7. The only reason I have any knowledge of the Mondragon is due to watching my son play Battlefield 1 on his PS4. That game is very well done with many obscure WW1 firearms, as well as the commonly known ones.

  8. It sounds like the General was wasting his talents. He should have been working for one or several of the arms companies.

  9. Congratulations on an excellent rifle too few of us know about. As they did with the AR15/M16 Series, why our U.S. Military Ordnance Bureau of that time failed to adopt, improve and manufacture the 1908 Mondragon Rifle under license, in lieu of the 1903 Springfield bolt action rifle, with half the magazine capacity, will forever remain a tactical mystery. Especially in the case of the latter rifle, the U.S. had to kick down design royalties and fees to Germany for patent infringements. With BAR/Browning Automatic Rifles chambered for 7mm Mauser as they were after WW2, backing up our WW1 Army Doughboys, Marines and British Commonwealth/Tommy Soldiers of the time, themselves armed with the Mondragon semi autos would’ve spelled a far quicker defeat of the Kaiser’s War Machine !

  10. Congratulations, and well done. Thank you for bringing your knowledge of this obscure piece of militaria, and the comprehensive article surrounding it.

  11. Further kudos for your excellent article about an obscure firearm. The “unobtainium,” however, is, perhaps, not so much your rifle as it is the sustained polite and respectful replies, thus far. Thank you.

  12. Love me some firearms history.
    I’ve been unsuccessful a few times during RIA auctions

    Thanks for a great article.

    • The author of has taken one of his rifles to the range and his range report is seen at:
      I do shoot my rifles with proper vintage ammunition at least once, as a general rule, as long as it is safe to do so without first modifying them (such as by swapping the “shooter’s kit” into a German G43/K43 to moderate the pressure of the 8mm Mauser cartridge and reduce the likelihood of the bolt flying backwards out of the receiver and into the shooter’s face). I also restore my rifles to their original functioning condition, if they are not that way when I acquire them, as I am doing with a French RSC1917 at the moment (and which other RSC1917 owners are also fond of doing, as one of the main components of the gas system is usually MIA). However, there are a few exceptions to my general rule and this is one of them, as is the museum piece that is the Royal Flying Corps modified Winchester 1907 SL. This Mondragon is so rare that, should anything break, borrowing an original part for duplication is a VERY BIG ASK, not to be made lightly even among the most respected collectors. The Winchester is basically one-of-a-kind historically speaking; the only other known British-proofed RFC-modified rifle known to have survived until today WAS held in the collection of the Imperial War Museum in London but went into private hands a couple of years ago and I do not know whose hands are fondling it now. Of course there are other examples of that not too uncommon Winchester rifle around — I just can’t bear the possibility of breaking anything on this one, though.

  13. I enjoyed reading you article. I especially like the logic you follow to imagine the rifles possible history. I had this particular rifle on my wish list of Mexican firearms and had the chance to see one in them at Chapultepec Museum in Mexico City. Strangely enough while surfing the net I happened across a gentlemen selling a collection of firearms which included a Mondragon right here in Houston Texas. When he pulled in from the rifle sleeve I instantly recognized the weapon I saw a year before in Mexico and bought in on the spot. The Seller was liquidating a late brothers estate and could not say where his brother acquired the weapon, so I will assume my weapon took a similar route as yours. Thanks again for sharing your article.


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