Mauser M1915 Selbstlader Infantry Rifle (Video)

The Mauser Selbstlader M1915 was the result of many years of work by the Mauser brothers to develop a semiautomatic rifle suitable for military use. They tried many different types of operating systems, and this one is a particularly unusual recoil-operated mechanism.

Only about 600 of these rifle were made, with about 400 of them being shorter carbine variants and the remaining few hundred infantry-pattern long rifles like this one. They use 25-round detachable magazines (which look like MG13 magazines but are not interchangeable with them), and are chambered for standard 8mm Mauser ammunition.

The locking system of the M1915 uses a pair of large flaps very much like the Mauser 06/08 pistol, but not a recoiling barrel like the pistol. Instead, a camming plate floats on a bit of spring tension in the rear of the receiver. Upon firing, the plate tends to stay in place because of inertia while the rest of the rifle recoils backwards. This differential movement makes the camming plate go forward relative to the rest of the weapon, and in doing so it unlocks the two flaps. Very unusual.

43 Comments

  1. Rather complicated, early “Inertia Operated” military rifle. It differs from current “Inertia Driven” shotguns with its unlocker piece’s mission which opening the breechbolt at the end of its forward travel, instead of compressing the unlocking media and performing the same task in its return, backward journey. Since the unlocking occurs through the forward rush of floating “Recoil Loader”, manual tracking of the breechbolt needs the manual forwarding of this block first and pulling the cocking handle backward after a provided retainer lever holding the inertia piece in its foremost position. The manualy tracked bolt frees the inertia block from its locked forth position at its returning to battery on position and a special safety lever mounted at the rear part of striker base prevents any accidental discharge if the inertia piece remains at its forward station and no manual tracking of breechbolt had been made. Ignition time of the striker seems rather long as negatiely effecting the accuracy, and since additional weights would slow down the recoiling speed, the rifle would go in malfunctioned. Though very well designed and made reflecting The Mauser genius and quality, it seems not a service rifle for heavy field and battle use. In fact, efforts of using the ınertia operation in the rifled shoulder guns should be useless by the cause of very fast bullet in the bore time and needing the near perfect gun and inertia masses ballance. IMHO.

    • This rifle walks the fine line between “far ahead of its time” and “result of a mad scientist on schnapps.” I imagine that there was a better approach to locking or delaying the bolt which simply hadn’t been invented at the time or had been claimed by someone else’s patent…

    • I like your “inertia operated” description. For some reason, I also like the way the flappers are behind the bolt, instead of cutouts in the receiver.

  2. Given what we know, I assume that having the flaps unlocked by an operating rod (gas action, anyone?) or just having a rotating or tilting bolt with a bolt accelerator would be much better than having a future shotgun action in the infantryman’s long arm… Did I mess up?

    • The ages in which this rifle designed, were the times of beginning of auto loading systems and the researchs for which known or possible one of them being much better and economical. Using the whole gun’s recoil as an actuator for breech block unlocking, instead of a movable barrel or a gas assisted rod, was really much ahead of that era since needing a design discipline getting into account of joining the fourth dimension of the machine elements; The time. It should be tought and tried by some genius and Mauser staffs acchieved this valuable improvement which, afterwards, been seen remaining short in the field and battle conditions. When metallurgy and gun powder technology improved, “Inertia Operation” found a way itself through the use of smooth bore shoulder guns in which much heavier massed missiles would be thrown out with much slower initial speeds which suiting into the tolerances of this simpler, cleaner and more economical system needs. IMHO.

      • Say if you sawed the butt stock off, and attached a wire stock to the rear of the recoil piece hypothetically. When you fired, the stock is preventing said piece from moving backwards but the gun can move within the piece. Car crash/not wearing a seat belt, car abruptly halts, out through the windshield you go. Kind of that isn’t it, inertia. The recoil piece is separate, in the sense that it can move independently from the rest of the gun. Which indeed it does do, in the opposite direction.

        • A bump fire stock, with a rod that connects to the recoil piece is another way to do it, possibly more reliably than relying on a “Jolt” like this Mauser, particularly if you held the rifle at a high angle because the recoil piece would have to overcome gravity.

          If I understand it correctly.

          • Simply a bumpfire stock should be more than enough and even “Doctor’s Order”. Connecting it with Inertia Piece would enarmously ascend the mass and spoil the critical balance between the whole gun and inertia piece and say; Firing the gun with the muzzle down, even the gravity may cause it working in simple blowback way or at least shorten the unlocking time. IMHO.

          • In regards the bumpfire stock, I meant simply attach a rod to the stock that the recoil piece would hit when the gun moves rearward via recoil, the recoil piece would then be shoved forward by said rod.

            I agree that firing it downwards would likely increase the speed of opening, given if said piece was heavy enough I assume it would open itself if you pointed the gun at the ground.

          • The inertia of floating piece should be enough for actuating the unlocking mechanism. The recoil of the gun would do what it needs. What important in this event, is the movement created by the recoil itself. Bumpfire stock would provide and ensure it in nearly all conditions. IMHO.

          • Ok, hmmm… I think the recoil pieces “inertia” is actuated when the rifles reward travel is halted by the butt stock hitting the shoulder.

            To use my car crash analogy, the recoil piece isn’t wearing a seatbelt and so flies through the metaphorical windscreen.

            I confess to not understanding the principle of inertia well.

            But if this rifle was allowed to travel rearwards without interruption, I don’t think this recoil piece would move- Are you saying it would move, because it remains sort of suspended in mid air while the rest of the rifle moves… Think that is what the author alluded to, suppose I am saying something different.

            Is it because the recoil piece is light, and the rifle heavy, and the recoil piece can move forward. I don’t really understand the Benelli system if that helps.

          • Though this Mauser rifle uses the Inertia operation with “one way ticket”, that is unlocking the breech at the end of its relatively forward travel, the current high priced shotgun cousins use it with “two way”, in which, breech opening occurs via not the end of inertia piece forward travel, but its returning back journey expelled by compessed inertia spring set at the end of one way travel. If noticed, latest samples include recoil absorbing devices transmiting minimum stroke to the users shoulder, but enabling whole recoil action of gun against to the these devices. In fact, they are similar devices to the bumpfire stocks and ensure the recoil movement in all conditions, say; Propping the back of shoulder stock against to a solid, rock steady thing giving no way of recoil at normal conditions.

          • Well I watched a video on the Benelli system…

            Say if a car was reversing, and stopped abruptly, and you weren’t wearing a seat belt, I imagine you’d go backwards against the seat- But if it didn’t break, wouldn’t you then go forward because the motion has to go somewhere and if nothing prevented you from going forward it would be through the windscreen again wouldn’t it.

            Does the Benelli system rely on someone holding the gun?

          • It should be related by the speed of gun’s recoil which should be based from case shape and bullet weight and initial velocity which usual in the full sized rifle rounds. Seemingly, this rifle has enough of them for this light inertia piece to unlock the flappers under high chamber pressure.

        • As known, all things tend to keep current movement or nonmoving situation until an outward force will be got. This should be the base of inertia operation. The inertia block, or piece, or floating thing will tend to keep its place when the sudden backward recoil jolt happens and relatively go forward on the rearwardly acting gun, like a person throwing forward in a sudden braked car. Inertia operation uses this relatively forward movement of floating piece; Either to unlocking the breech closure at its eventual travel( it should be a given distance at all) like this Mauser gun, or compress a stiff, spring like bouncing media to use its stored energy at its thrown back travel to unlock the breech and give some momentum to the breechblock, for the aid of extraction along with the residual gas pressure, like the slow initial velocity current shotguns. IMHO.

          • I just put a lighter on top of a cigarette packet, and pulled the packet away fast from underneath it. And the lighter didn’t move.

            Is that inertia, of the lighter? Thanks 🙂

          • If so, the recoil piece is the lighter, and the cigarette packet is the rifle. The flappers rollers are part of the rifle, so they just moved rearwards through the cammed surfaces on the recoil piece.

          • Well, the recoil piece did move forward… Er, it was sort of dragged back to it’s original spot by not wanting to leave.

            Fascinating stuff, he he.

          • Be quite stiff though… I mean, the cammed surfaces are behind the rollers. The rear of the rollers rest against the start of the cammed surfaces, which then move outwards. Suggesting forward movement would be retarded, in the sense of the recoil piece would be pulled rearward as a consequence of the above.

            Were as a jolt forward, might offer more of an impetus to open the flappers.

        • Inertia piece should be the one located over a carrier object. The given free way both at forth or back, would be the direction of act purposed to a certain task. In inertia operation guns, it should be at forth either to unlock or getting energy to unlock the back of breech, in single trigger doubles, it should be at back to disconnect the trigger/sear engagement when the recoiled shotgun to strike to the shoulder and bounce.

          • Cheers, here’s something else. The bolt would be pressing against the flappers, preventing blowback at the point the flappers would need to be moved by the recoil piece or them move through it etc. Would it really have enough ooomph, being lightweight.

  3. Ian,

    Thank you for a great website!

    This locking system is very interesting as it shows, at least to my mind, a lineage with what would become the roller delayed blow back system of mauser/cetme/h&k.

    Also, it would be interesting to know why mauser, after extensive experimentation, went this way with the rifle in the video and not with the likes of a gas system.

    Thank you again!

  4. I have fired one of these rifles and found the kick very heavy.

    Also it will only work if the cases are waxed otherwise they will shear.

  5. It’s amazing, but it seems more a “designer’s pet project” than a viable military action. One of those tings that are designed more to see if they could been actually made to work than to pretend they are better than other designs. Too much things have to go the right way for the rifle to function, while a military rifle must go bang in the most ample set of contitions that’s possible. IE, what would have been the effects of mud, ice or dirt on the inertia plate (that’s even partly exposed)?

    It has to be noted also that this is a semiauto action that can’t became an automatic one, since the rifle needs a distinct recoil movement for every shot.

  6. I can see how the inertia piece cams the locking flaps out from behind the bolt, but what actually moves the bolt backwards during firing? Does it open early enough so that residual gas pressure pushes the fired case and bolt back together?

    • This is what called “Balance” of the gun and inertial block masses. With a certain weight of gun, the lighter weight of floating inertia piece gives sticking cases needing lubrication like this rifle, and the heavier weighted inertia piece causes failure of extraction and ejection. Change in weight of the whole gun also will cause similar malfunctions. Longer “Bullet in the bore time” will grant easier balance assignements, like shotguns. The distance which inertia piece to reach and unlock the breechbolt and the power of its return spring should also be computed precisely. Not for rifles of all conditions.

    • Must be residual pressure, otherwise it would not open; there is no other momentum gathered to do that. A reader before mentioned strong recoil force and that makes sense; that bolt is just flying back.

  7. Ian,

    Thank you for an interesting post.

    To me the most surprising is that this mechanism shows a lineage to what would later become the manuser/cetme/hk delayed blowback mechanism. I don’t know if you would agree with this?

    It would also be interesting to know why, for example, a gas system was not used.

    Best regards

    • I can see the similarity in regards, rollers albeit different ones. But it isn’t operating on the same principle as is my understanding. On the Hk, it is just the weight of the bolt which holds the rollers in the receivers grooves untill pressure from blowback overcomes that resistance I.e. Of the rollers being in the grooves and the weight.

      • Even on the early 06h version, it’s debatable if recoil is what actuates it or the above. If tied a string around the trigger, then to a tree and threw the gun foward so the string became taught and pulled the trigger I think it would still fire.

        Thinking about recoil may have inspired it, not sure.

        • I think it would still function, as oppose fire once. Which if the rifle was travelling forwards, recoil would have to overcome this momentum making it unlikely to shift the shaped surfaces rearwards upon your shoulder stopping the rearward travel of the rifle.

          Take this Mauser for example, if this was fired while attached to a rack which ran on runners along a rail. Recoil would move the whole gun back along the rail, but if the rifle didn’t stop before this impetus ran ran out the recoil piece wouldn’t move I don’t think.

        • Agreed that the principles are not the same, however, to me this looks like a first iteration later to be refined in the 08. To expand, the principle is changed from recoil/idrtia to the more reliable blow back but at least to me the mechanism is very similar yet reversed and perhaps simplified. In later hk series the function of the camming plate in the rifle of the video is replaced by the camming piece set in the bolt body ariund the firing pin. Furthermore the hk series the (semi)lock is achieved just by the rollers being pushed out istead of drawn in by the locking piece (reversed from the earlier rifle from the video but similar in look) doing away with the flapper lock simplifying the action.

          Might just be me overinterpreting the whole thing but the similarity and same manufacturer makes me isee a connection.

          Also,sorry for the double post earlier. I did not understand that comments are moderated and thank youbfor your interesting comments.

  8. Neat rifle… It looks like the mud and filth of the trenches would have wreaked havoc on the mechanism though. I noticed that it seemed to be number stamped on pretty much every internal part, which seems to suggest that there may have been a lot of hand finishing done on the parts and a need to make sure the same parts found their way back into the same gun. I’d imagine that would make servicing in the field and replacing worn or broken parts a nightmare.

    Either way it’s a neat mechanism and it’s always cool to see the different thought processes that went into an autoloader design back then.

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