Disassembly and Reassembly Of the Remington Model 51

Have you ever heard of the Automatic Pistol, Caliber 30, Model 1918, Mark I or Mark II? Unless you’re an active member of the Remington Society, have read Roy Marcot’s History of Remington Firearms, or are really deeply into un covering once-upon-a-time military secrets, the answer is probably "no." What I’m guessing you have heard of, though, is the Pedersen Device. In 1915, an independent inventor named John D.

Pedersen informed Remington he’d developed a means of converting the bolt-action Springfield ’03 to an autoloader. After witnessing a demonstration, American ordnance officers instantly stamped the device "Top Secret." To throw off any German intelligence source regarding the true nature of their new beast, it was identified as a "Mark I Pistol." The invention replaced the standard Springfield bolt.

A soldier would remove and store it in a pouch on his belt, extract the device from a metal container similarly carried, insert it in the open breech of his rifle, and lock it in place with the magazine cutoff. A pistol-style magazine carrying 40 .30-caliber rounds of ball ammo would then be snapped into place extending out from the receiver at 45 degrees. Every time the trigger was pulled, one of those rounds would exit the barrel at 1300 feet per second.

Removing the invention and reinstalling the Springfield bolt returned the rifle to a single-shot .30-’06. Late in 1917, Pedersen’s "Mark I Pistol" was tested by the French Ordnance Board which immediately ordered 100,000 of them. This prompted U. S.

Army Ordnance to instruct Pedersen to adapt his device for service in the Model 1917 Enfield, and still keeping the ever-snooping Kaiser in the dark, tagged the conversion the "Model 1918 Pistol, Mark II." As such, it was carried by thousands of doughboys who led the offensive against an entrenched enemy in the spring of 1919. John Pedersen was no stranger to self-loading firearms. He had begun work on anew pocket pistol in 1913, filed for a patent in 1915, was interrupted by the war and refiled in 1919.

By the time the patent was approved in 1920, the pistol had already been in full production in Ilion, New York, and introduced as the Model 51. Chambered for the .380 Remington, it sold for $36.30. A .32 ACP version came along in 1921, selling for $25.00. By the time the Model 51 was discontinued in 1926, almost 65,000 had been produced. Let’s see, subtracting 1926 from 2006 means the Remington Model 51 has been out of production for 80 years.

Yet, with the possible exception of the Ballester Molina and a few foreign-made relics that would better serve their present owners as fishing weights, I receive more questions on the Technical Hotline about the Model 51 than any other pistol.

Before I get to the answers to the questions you have been asking, I want to extend our thanks to the folks at the Remington Museum who lent us photos of this long out-of-production gun and without whom this article would be incomplete. General Anatomy The Model 51 has a magazine capacity of seven. It was available in .380 or .32 ACP, hammerless with side ejection, and equipped with grip and thumb safeties.

The grip safety prevents any possible discharge of a chambered round unless the pistol is firmly in hand and the trigger pulled. When the grip safety extends out from the frame, it indicates the hammer is cocked. When the hammer is uncocked, the grip safety blends in with the frame. When raised, the thumb safety locks up the hammer hard and fast in the cocked position and can’t be raised when the hammer is in its fired (forward) position.

A third safety completely locks the sear when the magazine is removed to prohibit firing a cartridge that might have remained chambered. When the Model 51 was first introduced, a magazine disconnect—or safety—was not to be found on other pistols. A fourth safety feature is the gun’s solid breech in combination with the enclosed hammer. It prevents the hammer being moved to a cocked position, or anywhere near it, by dropping or striking the pistol against anything.

Cocking can only be accomplished by racking the slide to the rear. Also receiving special attention in the design were ergonomics. Multiple wax impressions were taken of human hands grasping the grip frame Figure 1. Figure 2. Figure 3. to determine the optimum angle in relation to the line of the bore. Lower felt recoil and more room to secure a better grip were enhanced by encircling the barrel with the action spring instead of locating the spring underneath.

Contributing to accuracy are the flat sighting rib, low sights, as well as the overall balance of a handgun that is 6-5/8 inches long, 9/10 inch wide, and weighing 21 ounces empty. The Model 51 Owners Manual All owner’s manuals should be so good and so complete. I realize they can’t be in these days populated by litigiously eager anti-gunners, all-too-often careless shooters, and the justifiable concerns they both raise in the legal offices of firearm manufacturers.

Evidently, the private right to self-defense or to sporting-gun ownership didn’t face many court challenges in the early 1920s. The Model 51 manual supports my supposition in that it is a factory-prepared guide to complete disassembly and reassembly. In fact, all the drawings included here have been reproduced from that 80-yearold booklet. Score one for the good old days. Field Stripping This isn’t quite as simple as it is with some current semi-autos. The

Remington Model 51 Semi-Automatic Pistol 1 Action Spring 12 Barrel Lock Pin 18 Cocking Roll 19 Cocking Roll Pin 24 Disconnector Lever 25 Disconnector Pin 26 Disconnector Spring 27 Disconnector Spring Plunger 28 Disconnector 29 Ejector 30 Ejector Pin magazine has to be removed or it will be impossible to take down the gun and, of course, you’ve already made certain that both the magazine and chamber are empty. Move the thumb safety down, depress the grip safety, and control the slide as it may move forward slightly.

Invert the pistol. Place the grip safety up against the web between your thumb and index finger, wrap 64 31 Ejector Spring 32 Extractor 36 Firing Pin 37 Firing Pin Spring 42 Grip Safety Pin 46 Hammer 55 Magazine Lock 56 Magazine Lock Follower 57 Magazine Lock Spring 61 Mainspring 62 Mainspring Plug your other fingers around the slide, then squeeze the grip safety (Figure 1).

With your other hand, grasp the muzzle end of the slide and move it to the rear until the semi-circular notch on its left edge is aligned with the barrel-lock pin (#12). Hold the slide in this position with your grip-safety hand. Pick up the magazine. Use its base to press inward on the lock from the right.

This will start the 63 Mainspring Plunger 64 Mainspring Rod 65 Mainspring Rod Pin 66 Mainspring Plug Retaining Pin 70 Receiver 75 Safety Lever 76 Sear 77 Sear Pin 78 Slide 80 Action Spring Bushing 81 Sear Lock 82 Sear Lock Lever 83 Sear Lock Lever Pin 84 Sear Lock Pin 85 Sear Lock Spring 91 Trigger 92 Trigger Lever 93 Trigger Pin 94 Trigger Spring 95 Trigger Spring Plunger 99 Cleaning Rod 281 Right Grip 306 Barrel 309 Breechblock 341 Grip Safety 352 Magazine (assembled) 381 Left Grip lock out of the frame.

The magazine base extension and your thumb will combine to lift out the lock pin. Still maintaining your hold with your grip-safety hand, move the slide half an inch rearward to expose the grooves cut near the barrel muzzle (#306). Hold onto the slide and turn the pistol as shown in Figure 2. With a thumb pressing against the slide, grasp the grooves between that thumb

Figure 4. Figure 5. and its associated forefinger. Depress the grip safety. Slip the slide/barrel assembly off the front of the frame, and don’t let go of the barrel (Figure 3). Now refer to Figure 4 and place the slide upside down in your free hand with the muzzle facing you. Pull on the barrel a little. Turn it counterclockwise until its lug stops and is held by the action spring (#1) against the shoulder in the slide. Push the barrel inward to raise the back end of the breechblock (#309) slightly.

Insert a fingernail between the cocking roll (#18) and the rear of the breechblock. (Lacking a longenough fingernail, you can substitute a very thin, small tool like apiece of hacksaw blade or credit card.) Push the breechblock farther to the rear and lift its back end over the slide lug. Now allow the breechblock to be pushed toward you under the pressure of the firing-pin spring (#37).

Lower the rear of the block so the firing pin (#36) and its spring will allow clearance for the block to be lifted free to the rear ( Figure 5). By tilting the muzzle, the firing-pin assembly will drop out of the barrel. The extractor (#32) never has to be removed from the breechblock except for replacement. If that appears to be necessary, insert the blade of a small screwdriver under the extractor claw, push outward and forward, then remove the part from the block with your fingers.

To release the barrel from the slide, regrip them as shown in Figure 4 and turn the barrel to the right (clockwise). This will disengage the barrel from the slide shoulder and allow it to be moved gently into the slide. Now reverse the position of the slide in your palm, placing its rear upward with the muzzle to the right. Push the barrel inward until it stops.

With thumb and forefinger of your free hand, with a finger inserted through the ejection port, pull the action-spring bushing (#80) forward and jerk it repeatedly against the pressure of the action spring to partially jar the bushing out of its slide mortise. Using the barrel as a lever (Figure 6), clear the bushing from the mortise, but be aware the action spring and bushing will snap backward on the barrel.

Assuming you will find a means to prevent those two potential travelers from exiting your premises, you can finally free them and the barrel from the slide. The pistol is now field stripped. Most modern firearm manuals come to a screeching halt at this point. Not so with the Model 51. The Total Dismount It’s possible to detail strip this pistol using its components.

I would and do recommend having a basic assortment of punches, a suitable drifting hammer, and other small tools on hand, but I’ll rely on the manual’s instructions pretty much as written, making changes for clarity only. The hammer (#46) is to be in its fired position with the magazine out. Holding the receiver as shown in Figure 7, lay the barrel on a firm surface and position the mainspring plug (#62) over the side of the barrel breech. Press down to push in the Figure 6. Figure 7. plug. Hard.

Push the grip-safety pin (#42) out with the firing pin. Remove the grip-safety assembly (#341). If you need to remove or replace the mainspring (#61), press down on the mainspring plug as before—hard— and push out the mainspring-plunger retaining pin. The mainspring assembly composed of spring, plunger (#63), and plug can now be removed from the grip frame and separated. Examine the grip frame. It’s a bit unusual in that it houses no grip bushings.

To remove the grips on a Model 51, you hold the receiver in one hand and push the grip downward until it stops. Then, raising the rear edge first, use the thumb and forefinger of the free hand to lift it clear. The firing pin can be used again to push out the sear-lock pin (#84) and set up the sear-lock assembly (#81) for removal. Now cock the hammer. Move the safety lever (#75) forward to uncover the sear-pin hole, then use the firing pin yet again to push the safety lever and sear pin (#77) out right to left.

Like an M1911, the trigger bow of the Model 51 passes around the magazine. Squeeze the long arms

of the bow together and shake out the sear (#76), the hammer with mainspring rod attached (#46), and the disconnector assembly (#28). Further disassembly of the hammer and disconnector assemblies isn’t recommended except for replacement of parts, in which case both assemblies can be taken down by pushing out the disconnector pin (#25) and mainspring-rod pin (#64), after memorizing the relationships of such parts as the disconnector lever (#24), plunger (#27) and spring (#26). Hold the receiver left-side upward.

Place a thumb over the grooved end of the magazine lock (#56). Here comes the firing pin one more time. Insert its point in the frame cut adjacent to the end directly opposite the end with your thumb on it. Push the lock out. Disregard opposition from the trigger-lever spring (#94), pull the trigger (#91) straight back, and it will exit the receiver. The trigger lever (#92), plunger (#95), and spring can be separated after drifting out the trigger pin (#93).

This dismantling shouldn’t be needed unless replacement parts are required. This completes the total disassembly of the pistol. Remington, however, didn’t stop there. They go on to tell how to reassemble a Model 51 in 15 steps, which I’ll detail below. Reassembly 1. Start in the trigger from the rear of the receiver with the trigger lever up. Depress the lever so it will pass through its pocket at the upper rear of the trigger guard. 2. Assemble the magazine-lock follower to its spring.

Hold the pistol as you did when removing the magazine lock. Insert the lock and hold it in place with a finger. Drop the follower into position from the opposite side of the lock, positioning the collar of the follower on the end of the lock. Use the handy-dandy firing pin or a properly sized punch to push the follower subassembly down as you apply upward pressure to the lock. When the two parts click together, you can let up on all pressure and the lock will come to its installed position. 3.

Drop the disconnector into place with the sloping surface of its upper end facing rearward. Squeeze the long arms of the trigger bow together, and engage the lower end of the disconnector with the notched bar affixed to the back of the bow. You may want to tip the receiver forward, making this step easier. Reinstall the trigger pin. 4. Insert the hammer with the bend of its mainspring rod facing forward. Secure with the safety-lever pin and place the hammer in its fired position. 5.

If you’ve taken the sear-lock spring off, put it back in. Do the same with the sear-lock lever, retaining it in place with a slave pin. Reinstall the sear from the rear with its hammer-engagement surface upwards, as shown in the cutaway photo. Align the searpin hole with the matching one in the frame and insert the sear pin. 6. Use the hammer-mainspring rod to raise the hammer to a fired position and hold it with a finger.

Insert the sear lock, spring installed, and press the lock down to compress the spring and force the rod through the hole in the receiver’s lug. After aligning, install the sear-lock pin right to left in the upper hole while pushing out the slave pin. Now align the large hole in the bottom of the sear-lock lever with the unoccupied sear-lock pin hole in the frame and install that pin. 7. Replace the grips by reversing the disassembly process. 8.

Being certain to have the end of the hammer’s mainspring rod (strut) properly seated against the mainspring plunger, reinstall the mainspring-assembly components and, yes, you will have to press inward again—hard—on the mainspring plug to install the retaining pin. 9. Place the grip safety in position and secure it with its pin after pressing the mainspring plug inward one more time—hard. So much for the receiver. 10. Put the action spring back in the slide and fit the bushing on the spring’s back end.

Compress the spring in order to start the bushing into its slide mortise. 11. Insert the barrel. Press it and the bushing completely into the mortise. Push the barrel toward the muzzle, and lock it in position by turning it to the right. 12. Preassemble the firing pin and its spring. Hold the slide with its muzzle end toward you. Insert the front end of the firing-pin subassembly in the barrel breech, then lower the assembly’s back end to slide down the sloping surface of the breechblock lug in the slide.

As the firing pin comes into alignment with its lug hole, raise the muzzle and the pin assembly will slide home. 13. Drop the front of the breechblock into place, then lower its rear and push it aft with finger pressure applied to the front of the block. The breechblock will snap into position. The slide is now assembled. 14. Hold the receiver and slide as in Figure 3, except with the hammer forward and the ejector down. Fit the two main components together, then push the slide back until it contacts the hammer.

Turn the barrel so the lug aligns with its receiver slot. Release the barrel. Cock the hammer. While depressing the grip safety, push the slide back to alignment with the receiver. 15. Replace the barrel-lock pin and insert the magazine. Conclusions If the pistol is to be stored for an extended length of time, make certain it is empty. Also, the magazine should remain empty with the hammer in the fired position. The latter two measures will avoid any possibility of the related springs taking a set during storage. ■