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Antique Military Firearms
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This is a mint condition, probably unissued, scarce, and original Springfield Armory Model 1866 Trapdoor Rifle, also known as the Second Allin Alteration Rifle, in .50-70 caliber. 


While the American Civil War was predominantly an Infantryman's war using muzzle loading, percussion cap ignition rifles, the use of breech loading, cartridge-firing weapons (principally carbines) left an indelible mark on both the US Army and weapons designers in the United States. The Army's experience during the Civil War left post-war Army leaders with two distinct impressions.

First, the accuracy and long-range of modern infantry rifles made the linear, Napoleonic-style of infantry tactics obsolete. And second, the need for faster firing weapons was a necessity for modern infantry combat. The result was the formation of a special board by the War Department to select a new breech-loading rifle. Once the board was formed, it developed a list of requirements for a new breech-loading rifle and sent requests for submissions to all known arms manufacturers and to the National Armory at Springfield. The principal requirements of the new arm were straightforward: a breech-loading firearm chambered for a self-primed, metallic cartridge.

When Springfield Armory received the request for the board, it assigned the responsibility for developing the Springfield design to Springfield's Master Armorer, Erskine S. Allin.  Allin's design was both simple and practical. His design, oddly enough, involved the conversion of the earlier Model 1861 Pattern Rifle Musket that was used during the Civil War instead of the later Model 1863 and 1864 Rifle Muskets. Many thousands of these muzzle-loading rifles were on hand at Springfield

after having been returned following the demobilization of the Union Army. Allin's design involved cutting a section out of the breech end of the standard Model 1861 .58 caliber barrel and fitting a hinged breechblock into the cutout space. This was the "trap door" design that became the standard design for the US rifle for the next 25 plus years.

Several foreign and domestic US designs were also submitted to the board in late 1865. The board ultimately chose Allin's Springfield-submitted design. Although many have opined over the years that one of the main reasons for the board's selection of Allin's design was its familiarity to the board's members (it looked very similar to the muzzle loading Model 1861), the real reason probably had more to do with the Army's tiny budget after the end of the Civil War and the relatively low cost of converting existing arms compared to procurement of an entirely new design. The War Department approved the board's recommendation and Springfield was directed to produce 5,000 Model 1865 breech loading rifles, which became known as the "First Allin" Rifle.

The Model 1865 "First Allin" Rifles were finished in 1866 and issued to soldiers in the field. The Model 1865 fired a short, copper-cased, .58 caliber rimfire cartridge with a powder charge of 60 grains and a 500-grain bullet. Reports from these units identified several problems with the new rifles. First, the copper cartridge case had a weak case head that was often torn off during extraction, leaving the rest of the case inside the chamber. Ballistically, the .58 caliber round was also considered underpowered. And the breech system itself was considered too fragile with problematic extraction and ejection components. The problems identified were severe enough that Springfield made the decision to completely redesign the breech action and develop an entirely new round.

The new cartridge that was designed was based around a .50 caliber bullet that had a more pointed tip than the earlier .58 caliber round. The case was also significantly different with a longer overall case length and centerfire ignition system instead of the earlier rimfire design. The new case held 70 grains of black powder, giving the new round a significantly higher muzzle velocity than its predecessor. Springfield also designed a new breech that was stronger and had more robust components.

The new design was, unlike the earlier Model 1864 "First Allin" Rifle, based on the later Civil War issued Model 1863 and 1864 Rifles. The concept was the same, however, in that the rear portion of the original barrel was cut away and the new breechblock was hinged in the "trap door" style. The smaller diameter of the bullet necessitated a more radical change to the existing Model 1863 barrels. The .58 caliber rifled barrels were reamed out along the entire length to a diameter of .640 inches and then fitted with a .50 caliber liner or barrel insert that was brazed in place at the muzzle and breech.

This new rifle was designated the US Model 1866 Rifle, also known as the "Second Allin" Rifle and it performed much better than the Model 1865 First Allin Rifle. The Model 1866 saw active combat service soon after it was issued and was considered instrumental in the Army's defeat of Sioux Indians under Chief Red Cloud at the Wagon Box Fight and Hayfield Fight, both occurring in August 1867 along the Bozeman Trail in the Wyoming and Montana Territories.

The exact number of Springfield Armory manufactured (modified) Model 1866 Rifles is not entirely clear. Norm Flayderman's Guide to Antique American Firearms, the benchmark text on American weapons, states that only about 25,000 were manufactured. Richard Hosmer's fine work on .58 and .50 caliber Springfield Rifles lists approximately 52,300 Model 1866 Springfield Rifles manufactured with most produced in 1867, plus a few hundred additional rifles in 1868 and 1869. Regardless of the total number made, which is still a small number comparatively speaking even if Hosmer's number is used, when the Model 1866 was eventually replaced a few years later with the US Model 1868 Rifle, most of the existing Model 1866 Rifles were purchased by the Remington Arms Company and were resold to the French for use during the Franco-Prussian War of 1870-1871. While some of these rifles made it back to the United States over the years, the majority did not, making the Model 1866 a historically significant and very scarce example of American military firearms design.

As noted, this particular Springfield US Model 1866 "Second Allin" Trapdoor .50 caliber Rifle is in mint, original condition and was probably never issued. The Lockplate is the correct Civil War era Model 1863/64 Lockplate that is correctly marked "1864" to the rear of the Hammer. Forward of the Hammer is the federal spread eagle with the eagle looking towards the muzzle. The eagle bears the large shield, and the detail is still exceptionally fine. Just forward of the eagle is a crisp, serif "U.S./SPRINGFIELD" stamp.

The outer, flat surface of the Lockplate still retains virtually all of the original color case-hardened finish with even more present on the edges.  The original Hammer is present, and it also retains the vast majority of its original case-hardened finish on both sides. The in-shield knurling on the thumb piece of the Hammer is still crisp. The face of the Hammer, correctly, comes together with the rear of the Breechblock comb to form a line that is not perpendicular to the barrel, which makes the Model 1866 unique among all Trapdoor models. The original single-slot, rounded face Hammer Screw is present and is in fine condition and is unmarred.

The interior of the lock mechanism is also in mint condition.  The interior wall of the lock plate retains all of its original color case-hardened finish.  The interior wall has numerous inspection stamps, including a serif “X,” a serif “U,” a serif “L,” and a “5” stamp.  The Hammer Main Spring is still very strong and retains all of its original heat tempered finish.  The Bridle retains all of its original oil quenched finish as does the original two-position Tumbler, which is marked with a “8” stamp, the Sear, which is marked with a serif “D” stamp, and the Tumbler Lever Arm, which is marked with a “2” stamp.  The Sear Spring retains all of its blue tempered finish and is marked with a “U” stamp.  All three internal lock mechanism screws retain all of their dark oil finish, and all have unmarred slots.  Both lock plate screw washers are present on the stock, and both remain correctly in the white and retain their beautiful national armory bright finish.  Both original lock screws also retain the majority of their original national armory bright finish on the heads.

The original Thumb Latch retains the majority of its original dark oil-quenched finish with virtually no wear. The top of the Thumb Latch is correctly smooth and the single-slot, rounded head Latch Screw is only slightly marred. The Thumb Latch is the second of two types used on the Model 1866, with the integrated, machined cam. The Cam Cap and single-slot Cam Latch Screw are in fine condition retaining most of their original blackened oil quenched finish.  This second type of cam was introduced at around production number 7,000.

The Breech Block is the correct type with the flat-top firing pin housing or comb. The top surface of the Breech Block still retains virtually all of its original oil quenched blackened finish that is only slightly thinning. The bottom of the Breech Block is the straight, cylindrical type that retains 99% of its original, dark blackened oil quenched finish. There is a serif “Q” inspection stamp on the bottom of the Breech Block. The top, forward section of the Breech Block has a crisp "1866/small eagle head" stamp. There is, correctly, no sighting notch in the Breech Block Hinge, which is also unique among Springfield Trapdoor weapons.

The Breech Block opens the full 160 degrees, which is far more than any other Trapdoor Breech Block. The Firing Pin, which is retracted by a Firing Pin Spring that is still strong, is secured at the end of the comb by a Spanner Head Retaining Collar, which retains all of its original dark finish. The single-slot Hinge Screw is in mint condition with no marring and is secured on the left side of the hinge by the original two-part Jam Nut, which also retains the vast majority of its original finish. The Hinge Strap is in fine condition and retains the majority of its original, but now thinning, oil blackened finish. Both single-slot Hinge Strap Screws are present and are in excellent condition.  The breech face exhibits minimal signs of firing.  The breech of the barrel is in very good plus mint condition, which still retains all of its national armory bright finish with areas of foxing and staining.  The original Ejector is present, and it is secured by the original Ejector Screw on the bottom of the barrel, both of which retain 99% of their original dark oil finish.  The original Extractor and Spring are also present, and both also retain virtually all of their original dark oil finish. 

The Stock on this rifle is the original in mint, unissued condition with a only a very few minor storage dings, but there are no cracks or chips noted.  Model 1866 Rifles used one of two types of stocks. The first were existing, but unissued US Model 1863/64 Civil War-era stocks that were subsequently modified to accommodate Erskine Allin's mechanism. The second type of stock was a new, black walnut stock that was milled from a stock blank especially for the Model 1866 Rifle and its unique mechanism.

This particular stock is the earlier, Civil War Model 1863/64 Stock that was modified in 1866 for the alteration and it still retains its original oiled finish.  On the left stock flat is the oval-end, boxed cartouche with script letters "MTH" inside the box.  It is not currently known who the “MTH” cartouche belongs to, be his known to have inspected some number of Springfield Model 1861 Rifles.  Below that is the oval with script “ESA” stamp of Erskine S. Allin, Master Armorer at Springfield and the designer of this alteration.  The bottom of the stock wrist, just to the rear of the Trigger Plate, is a serif “CD” inspection stamp.  In the tang mortise is a crisp, serif “E” inspection stamp. The Nose Cap on the Stock is still in its original National Armory Bright finish that is in fine condition.  The original Nose Cap Screw is present, and it retains the majority of its original dark oil finish with a slightly marred slot.  All of the inletting for the lock and trapdoor mechanism are as crisp as the day they were made at Springfield Armory.

The Butt Plate is the correct and original curved profile, convex surface type with crisp "US" stamp on the Tang. Both the Tang Screw and Butt Plate Screw are the correct single-slot, rounded face type that are in mint condition with no marring of the slot. The Butt Plate itself still retains virtually all of its original national armory bright finish, that now exhibits a pewter and plum.

The Rear Sight on this Model 1866 Rifle is the correct US Model 1863/64 Rear Sight from the Civil War. The Rear Sight Base is attached to the top of the barrel in a dovetail and is held in place by its original Spanner Head Screw, and this Screw and the "floor" of the Rear Sight Base in which the Spanner Nut secures the sight are both in mint condition and retain the majority of the original dark oil finish with the sides retaining the majority of the correct national armory bright finish. The Elevation Leaf is correctly marked for 100, 300 and 500 yards with a 700-yard notch at the top of the Leaf. The Elevation Leaf retains the vast majority of its original blued finish. The Leaf Screw secures from the left side and the Leaf Screw's single-slot is unmarred.

The Barrel on this Model 1866 Rifle is the original modified .58 caliber Model 1863 muzzle-loading Barrel that is 40" long. The Model 1863 Barrels used on the Model 1866 Rifles were reamed out to a diameter of .640" the entire length of the Barrel and were then fitted with a .50 caliber, rifled Barrel Liner that was brazed at the end and the Barrel crowned. The braze line on this Barrel is barely noticeable and the Liner is still secure. The bore has the 3-groove rifling, and the bore is in very fine condition with a mirror finish and strong rifling and only very minor frosting in the lands and grooves. The original Front Sight is present and is still securely brazed to the top of the Barrel. The external surface of the barrel remains in its original bright finish with only a very few, minor areas of staining.  The sides of the barrel retains several of the original, Civil War-era inspection stamps.  On the right, rear of the barrel is a serif “B” inspection stamp.  The barrel is in in mint condition.  On the left side of the barrel, below the hinge is a serif “X” stamp.  On the far left, rear of the barrel is a serif “TL” inspection stamp, and the full Civil War-era eagle head stamp is still visible. 


The Barrel Tang is still in National Armory Bright and is very clean and the single-slot, flat head Tang Screw is in mint condition with an unmarred slot.  The breech plug itself still retains the majority of its original dark, oil quenched finish.  The rear end of the barrel and the back portion of the breech plug both retain numerous inspection stamps.

The Trigger Guard and Trigger Plate assembly remain with all of their original National Armory Bright finish that is in mint condition. The original Trigger is present, and it retains 99% of its original oil blackened finish throughout. The Trigger operates smoothly and still releases the Hammer crisply. The original Lower Sling Swivel Assembly is present along with the Lower Sling Swivel Screw.  Both Trigger Plate Screws, which are round head, single-slot Screws, are present and both are unmarred.

The Lower Barrel Band has the correct, serif "U" stamp on the right side and retains all of its National Armory Bright finish with only some small foxing present and exhibits minor pinprick pitting. The adjacent Band Spring is in fine condition.  The Middle Barrel Band has the original Sling Swivel present and attached with a correct Split Shank Swivel that is retained by a flat head, single-slot Band Screw that is unmarred. The Middle Band has the correct serif "U" stamp on the right side, and it retains all of its original bright finish and is in fine condition. The Middle Band Retaining Spring is present and is in fine condition.

The Upper Band also has the correct serif “U” stamp on the right side, and it retains most of its original National Armory Bright finish with some foxing and minor pinprick pitting.  The Upper Band Spring is in fine condition.  The original slotted-head Ramrod is present and is 38 3/4" long and it retains all of its National Armory Bright finish. The Ramrod, when stowed, is correctly 1 1/8" short of the muzzle. 

This is rare, historically significant, and mint condition example of the Springfield US Model 1866 "Second Allin" Conversion, .50-70 caliber Trapdoor Rifle that is in its 100% original configuration.  This is a museum quality example and would be impossible to upgrade.  This Model 1866 Rifle is in firing condition.