First Pattern 1865 Allin Conversion – Trapdoor Springfield at RIA

As the US Civil War drew to a close, it was quite apparent to everyone that muzzleloading rifles were obsolete, and any military force wishing to remain relevant would need to adopt cartridge-firing weapons. However, the Union arsenals had a million or more muzzleloading rifled muskets still on hand. How to modernize the weaponry without simply throwing away all those existing guns?

The task was put to Springfield Arsenal master armorer Erskine Allin in 1865, and he devised a “trapdoor” style of conversion to turn an old Springfield muzzleloader into a breechloader. He had the benefit of having seen the previous year’s extensive trials of breechloaders, but the final product was his combination of what he judged to be the best elements of the ideas available.

The result has long been known colloquially as the Trapdoor Springfield, and this 1865 model was the very first of them. It was still in .58 caliber, and used a rather complex extractor system. It would soon be revised to make improvements to it, and ultimately a .45-70 model became standard for US infantry and cavalry forces – and remained their standard until the adoption of the Krag-Jorgensen in the 1890s.


    • But remember that brand-new Mauser rifle is much more expensive than breech-loading conversion. I don’t know exact numbers of $$$ needed for one example of each fire-arms, but I bet it is 1 Mauser for few converted rifles.

      • Drat! I forgot about that elephant in the room. What about improvising a sort of magazine to go with the conversion until a new gun can be developed? It will be hard, but better than fumbling in your belt for ammunition every time the trigger is pulled.

          • Those clips had to be yanked out by strings, but they were better than fumbling with individual rounds from a pouch.

            Some smart guy thought about adding a cartridge box to the Trapdoor Springfield to avoid the old “fumble with the belt” shenanigans that would occur in battle, especially when shooting prone. Sadly, his idea was not implemented and the reservists armed with the late Trapdoor Springfield rifles nearly got massacred by their Spanish opponents…

        • “magazine to go with the conversion”
          In 1880s in Russia various repeating rifle were tested (all tested systems: 128 in this number systems of Russian inventors: 38). Some were conversion of single-shot Berdan rifle, most have various drawbacks (awkward handling, high price, low reliability, lowered stock and/or receiver durability), most successful was that designed by Игнатович which features 5-round (1885) or 10-round (1886) magazine sticking to left (so it doesn’t need cutting in stock which would lower stock durability), Игнатович design passed trials and order for 2000 examples (for troop trials) was planned but it was deleted by general Вельтищев (designer of different system which proved be inferior).

  1. Fascinating Ian!
    I often wondered what happened during the transition from the Civil War cap and ball to the 1873 Springfield I use to own.
    I did not know that the immediate post Civil War trap door had spring loaded firing pins albeit the later models abandoned them for the simple floating firing pin in the 1873 trapdoor Springfield.
    Interestingly, my new Pedersoli “Springfield 1873” 45-70 HAS a spring retracting firing pin– coming full circle from 1865-66!
    Also, viewing your RIA gun I see that the cleaning rod was not upgraded from the function of ramming mini balls down the barrels. There is no slot on the rod to take a cleaning patch.
    Thanks for another great presentation and looking forward to saying hi to you at the Fairgrounds on Friday.

  2. I’ve never forgotten the War Department report of the 37,574 rifled muskets salvaged from the battle of Gettysburg; one had 23 rounds in the barrel,6,000 had from 3 to 10 rounds each,12,00 had 2, 6,000 had 1. The remainder were unloaded. Under the stress of combat, a soldier doesn’t have the time to use the ram-rod index to see if his rifle is loaded or not. Breech loading for the win!

    • “Breech loading for the win!”
      It gives also big improvement in rate-of-fire, according to V.G.Fyodorov (Эволюция стрелкового оружия) states that following RoF:
      7-line flint smooth-bore muzzle-loader around 1800 – 1 shot per minute
      7-line percussion smooth-bore muzzle-loader model 1844 – 2 shots per minute
      7-line percussion muzzle-loading rifle model 1854 – 2 shots per minute
      6-line percussion muzzle-loading rifle model 1856 – 2 shots per minute
      6-line Karle rifle model 1868 – 6 shots per minute
      6-line Krnka rifle model 1869 – 6 shots per minute
      4,2-line infantry Berdan rifle No.2 (1870) – 8 shots per minute
      3-line infantry rifle model 1891 – 12 shots per minute
      (line is old Russian length unit, 10 line = 1 inch so 1 line = 0.1 inch)
      So as you might calculate Berdan rifle has 4x bigger RoF than earlier muzzle-loaders! That is more than percussion has over flint (2x bigger RoF) or repeating rifle (Model 1891) has over single-shot brech-loader (1,5x bigger RoF)

      • If you wonder was Karle rifle (Винтовка Карле) it is conversion from muzzle-loaders (6-line model 1856 rifle) to needle-fire, for more information (in Russian) about it click here: http://alex—
        Even if you don’t know Russian you can see drawings (click графическая часть) or blueprints (click Чертежи винтовки Карле, часть 2); all is .djvu format

    • As long as you are fighting other guys with muskets, it evens out.
      The dog gone problem is that when the primer goes off and you are surrounded by the noise and smoke, not to mention minie and cannon balls whizzing by and your friends falling around you, you don’t always realize that the gun is not firing. You are more of an automaton with drilled in programming, no time to think about it. Load and shoot, load and shoot.
      And once you have time to figure out a problem you don’t bother trying to fix it, you throw it down and get another.

  3. “However, the Union arsenals had a million or more muzzleloading rifled muskets still on hand. How to modernize the weaponry without simply throwing away all those existing guns?”
    It was also hot topic for all European forces. See for comparison Russian Krnka rifle, BTW: it fired 15.24mm (.60″) cartridge with inside lubricated bullet, considering that .44 Russian is NOT first cartridge of that type:

  4. I have 3 of the next model, the 1866 in .50-70. my great-great-grandfather was a supply sergeant with the Salem,MA militia and after they got back from Cuba (spanish-american war), he brought 3 home. they likely haven’t been fired since.

  5. It’s interesting that, even though this was developed as a conversion, very few converted Springfield 1863 rifled muskets saw service in the military. By the time the 1873 trapdoor was adopted these guns were new made, not converted from old rifles. (The 1866 trapdoor had a sleeved barrel to adapt it to the .50-70 Govt., so probably not much cheaper in time and money than making new rifles.)

    The winner for “most used converted muzzle-loader” would probably go to the Snider-Enfield.

    • According to W.H.B. Smith, the punch line is that Jacob Snider was a design engineer at Springfield when he first proposed his conversion breech. Allin, his boss, was infuriated that Snider was trying to “upstage” him, and got him hauled in front of a review board for “insubordination”(!).

      Snider ended up being fired from Springfield (he was technically a civilian War Dept. employee), and being rather fed up with the whole business, took his design to Enfield Lock.

      The rest, as they say, is history.

      The second punchline is that Allin’s breech was basically a slightly modified version of Hiram Berdan’s trapdoor breech used on the “Berdan I” breechloading conversion in Russia. No, Berdan never received any royalties on it, either. I suspect Allin was not one of his BFFs.

      The Snider breech is a lot stronger than the Allin. Years ago, I read an article in one Gun Digest Annual in which one “expert” claimed the Allin was stronger than the Remington Rolling Block. His “proof”? In an overpressure event, the Allin “trapdoor” invariably blew open before the barrel split. Never mind that if you’re behind the darned thing, you want the barrel to fail before the breech does.

      I don’t think he understood pressure events very well.

      All that really holds the Allin (or Berdan) breech shut against, say, a blown case head failure is the spring latch. If that latch is overcome (or just shears) the breech flips open, probably fracturing the hinge pin. The shooter gets a face-full of hot powder gas and brass fragments.

      The Remington rolling block is famous for its strength, like the time a French testing committee loaded one breech to muzzle with a dozen bullets and the rest of the barrel full of powder plus triple wads. Then fired it from behind an armor plate with a long lanyard. Their report? “Nothing extraordinary happened”- except to the target.

      The Snider may be even stronger than the Remington. It’s basically a steel “brick” in a steel “box”. Its linear hinge pin does not permit rotation upward, except in the same axis as the barrel. Its spring-latch is really just there to keep it from coming open due to gravity when the rifle is inverted.

      A breech failure, Allin-style, in a Snider requires compressing steel upon steel. Which isn’t likely to happen with blackpowder pressures.

      BTW, according to Barnes, the .58 rimfire and centerfire (Berdan inside-primed) rounds for the conversion all had about the same ballistics. Bullets ranged from 460 to 530 grains, muzzle velocities from 1150 to 1250 F/S, ME from a low of 1400 to a high of about 1600 foot-pounds. The 530-grain carbine load (short case) left the muzzle at about 925 for 1012 FPE.

      Today, we’d call them “brush range deer loads”, which for their intended (military) purpose was probably good enough.



      • “which for their intended (military) purpose”
        V.G.Fyodrov (Эволюция стрелкового оружия) states 600 as sights maximal range (using шаг – old Russian unit, 1 шаг = 88,9cm = 0,889m, so it is 533.4 in meters) for 6-line infantry Krnka rifle

        • “The Remington rolling block is famous for its strength”
          In 1860s it was considered as best breech-loader available by Norway-Sweden alliance, see photos of Swedish rolling block rifles here:

          Initially it fire 12.17x44R rim-fire cartridge, later it was redesigned to handle more powerful 8x58mm RD center-fire cartridge.
          Article in Wikipedia titled Remington Rolling Block rifle has a long list of cartridge chambered in Remington Rolling Block, it ends with note Various Target/Sporting/Hunting Calibers. Which was most powerful cartridge ever used in Remington Rolling Block?

          • That’s hard to say, because for the past century rebarreling rolling block actions for a variety of more modern cartridges (including wildcats) has been a popular way to create custom single-shots here in the U.S., and probably elsewhere as well. Rather like Martini “falling-block” actions have been during the same period.

            I personally have seen rolling blocks rebarreled to .220 Swift, .30 and .357 Herrett, .357 and .44 Remington Magnum, .348 Winchester, and one in .450 Alaskan which is of course a necked-up and reformed .348.

            Also note that around the turn of the last century, Remington did a land-office business selling rolling blocks in 7 x 57 Mauser to various foreign governments, notably Mexico, to supplement their bolt-action Mausers for “Guardia Civil” or similar units.

            As a general rule, I’d say any cartridge in the pressure range of those mentioned would probably be a reasonable choice for a rebarreled Remington rolling block.

            And .220 Swift on down to the .357 Magnum takes in a lot of territory, pressure-wise.



          • “hard to say”
            Ok, I check modern reproduction which are chambered for following cartridge (but remember than 21th century metallurgy is not exactly equal to that of 19th century):
            Davide Pedersoli:
            .30-30 Winchester, .38-55 Winchester, .45-70, .45-90, .357 Magnum, .22 Long rifle, .45 Long Colt, .44-40 Winchester
            .38-55, .30-30, .45-70
            Uberti (scaled-down version of Rolling Block):
            .17 HMR, .22 Hornet, .22 Long Rifle, .22 Magnum, .357 Magnum

  6. I for one would love to see a series here that a least gave a bit of information on conversions of this type from around the world.

    Also a question. Did the Swiss ever give serious consideration to such a conversion or ever consider a single shot rifle?

    • Martin:

      Milbank-Amsler conversion. 1867, called the 42/59/67 Milbank Amsler. Single shot conversion of apparently several Swiss rifle-muskets. I believe that they were designing a single shot Vetterli but the Winchester 65-66 convinced them that the tube magazine was needed. They also had purchased 15,000 Peabody 1867 rifles. These two weapons were while they waited for the development of the tube magazine Vetterli and then the production of same. The Swiss were still upgrading their Peabodys through 1877.
      Of course the US went the other way, creating the Springfield trapdoor and just toying with repeaters for 25 years. The US had the luxury knowing it could not be invaded without a very long time of warning and also had no overseas possessions to protect. We were not interfering in anyone’s business either, the French having retreated from Mexico.

    • Martin:

      Apparently a collection of Milbank Amslers in their different variations have just popped up on gunbroker including the infantry musket conversion. very nice condition and very nice color pics.

      Not cheap, 2.2-1.8K a pop.

  7. From what I’ve read, I believe the Allin was chosen because it was developed “in house” and the government didn’t have to pay royalties on the design. I’ve often wondered about the cost/time effectiveness of such conversions, considering the short service life of the initial runs. Perhaps it would have been more cost effective to simply unload the existing stocks of muzzle-loaders on the surplus market, particularly to less developed countries who would welcome something better than a matchlock or jezail. The funds could be used to procure a more advanced repeating firearm, particularly when the 1873 Trapdoor was developed from scratch at a time when more advanced designs were on the drawing board. As much as I love shooting my Trapdoors, I’d much prefer a Lee/Sharps Model 1879 (or Remington-Lee), a Mauser 71/84 or a Vetterli if I were being charged by a bunch of angry natives. Then again, the bean-counters and drivers of the armor-plated desks have different priorities, I suppose. Although I am suspicious of their price lists, the Flayderman’s Guide to Antique Firearms has a pretty good section on the various breech-loading conversions developed after the Civil War. Some, like the Needham, have a really fascinating history.

  8. I also figure that the majority of these overloaded rifles found at Gettysburg were cast aside during the heat of battle in favor of another one that might fire. Raw numbers don’t always tell the whole story.

    Let’s do a little math to see how bad the situation might have been. Say half of the doubly loaded rifles were Union. That would leave 9,000 Union rifles overloaded to some degree or another. Ordnance reported that 4,500,000 musket rounds were used by the Union army at Gettysburg. Say half of those rounds were dropped or otherwise lost or wasted. That would leave 2,250,000 shots fired. So 2,250,000/9000 leaves about 250 shots fired per overloaded rifle found. Not great, but it puts a little different perspective on things.

    • I own a muzzle loading rifle, and what that War report pointed out to me was that in a time of stress a soldier can double load or more. They only carry so many paper cartridges, so while black powder is unlikely to blow up the musket, he is disarming himself. A breechloader cannot be double charged.

  9. One observation and one question.
    First, one often reads about “needle guns”- these are references to the trapdoors, not the Dreyse (e.g.: trapdoors look like there is a needle under the hammer).
    Was the 58 trapdoor a rimfire or centerfire, and if it was a centerfire, what kind was used?

    • This First Pattern 1865 Allin conversion was in .58 Musket rimfire. (Also referred to as .58-60-500) Here are some nice pics of these early cartridges:

      The second one from the left in the top picture was for the first pattern Allin.

      You’ll note that many of the early center-fire cartridges do not have a primer pocket. They use the internal Benet style primer where the cartridge case head needs to be soft enough to deform from the blow of the firing pin. This is why you’ll often see requirements in ordnance tests to check what happens when there is a case head failure, all too common with these early cartridge designs.

    • In the U.S., where the Dreyse “needle gun” was practically unknown at the time, “needle gun” was a common nickname for the Allin trapdoor conversion. This was due to its long firing pin through the breechblock, hit by the former percussion-cap musket hammer, in a fashion very similar to modern-day self-loading pistols with exposed hammers (Colt 1911, Beretta, etc.).

      The long firing pin was the “needle” part.

      There was also a pre-Allin breechloading alteration of the Model 1855 rifle-musket, that was an internal-hammer type with a similar firing-pin setup. Its breechblock opened to the right rather than upward. It had its bore reduced from .58 to .50 with a ratchet-rifled liner tube.

      A similar firing system with an outside hammer was used on the Morse alteration of the 1855 rifle musket, with a breechblock that opened upward and back, opposite the Allin’s arrangement. 2000 were ordered in 1858 by Ordnance, and $10,000 paid to Morse in advance. Then the contract was canceled with only 60 rifles completed.

      No, Morse didn’t return the advance. He later went on to design and build a similar system as a cavalry carbine for the Confederate Army in 1864-65. About 1,000 of those are believed to have been made, but few survive today.



  10. Greetings,
    Just an observation based on my unaltered 1864 Springfield, I do believe the hammer was replaced or heavily modified for this conversion. The nipple on an unaltered P1863 is where the locking leaver on the Allen conversion is located.

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