Remington Model 51 modification

By Kenneth C

Not too long ago I acquired a very nice Remington Model 51 in caliber .380. For those who don’t know the Remington M-51 was one of the ‘top of the line’ semi-automatic personal protection.380 pistols of the 1920s. In the US it’s only true competitor was the Colt .380. The actual production span of the M-51 was short and less than a decade.

The Great Depression played a large role in Remington’s decision to exit the pistol market entirely and thereafter focus on rifles and shotguns. The last Remington M-51 was assembled at Remington out of left over parts and left their factory in 1932.

Picture, unmodified M51


The design is a sleek semi-auto pistol, with a grip angle similar to that of the German Luger. This grip angle makes pointing with it almost instinctual, versus the less steep angle of the Colt and Savage pistols. Most of the M-51s were made in blued steel, as is my own. The gun was largely designed by a man John Browning himself called one of the best gun designers ever, John Pederson. Unlike the Colt, which is a delayed blow-back pistol, in which the slide begins moving rearward at the instant of firing, before the bullet has left the barrel, the M51 is something called a hesitation blow-back, in that the bullet has already left the gun’s barrel before the slide unlatches and begins moving rearward to eject the fired cartridge case (re-cocking the striker in the process), and on returning picking up a new cartridge from the magazine and chambering that next round. Because the chamber pressure is reduced by then, the recoil force of Pederson’s design is much less than that of other contemporary pistols. Although the unlocking mechanism of J. Browning’s pistol has been widely copied by many gun makers (i.e., Colt, Walther, FN, Glock etc.), because Pederson’s design was more expensive to manufacture, no other pistol made used Pederson’s unlocking design for the M-51.

The M51 has 3 different safeties. There is a magazine safety. Removing the magazine makes the gun incapable of firing. There is a grip safety which blocks the internal hammer from movement, unless the gun’s grip is being squeezed. The act of cocking the gun’s hammer moves the grip safety to an outwards position and that locks the hammer. The spring of the grip safety is strong, so a firm grip is needed to fire the gun before the trigger can be pulled. . The third safety is a thumb safety. Positioning it in an up position renders the gun incapable of firing. Flick it down with your thumb and the gun can fire, if the grip is being squeezed and a finger is on the trigger.

The three safeties working in combination make the M-51 one of the safest pistols of the pre-WW2 era. The grip angle and ergonomic design also made it one of the best pointing pistols of the 20th century. The superb internal design coupled with experienced craftsmen and good materials to make it with meant the gun was one of the more reliable pistols of the early 20th century. Where this weapon’s design fell down was the sights.

Intended for self defense the sights on the pistol can best be described as vestigial. The front and rear sights were machined into the slide and are a mere bump only 6 hundredths of an inch in height, i.e., 0.06 inches. Needless to say, that is tiny enough to be virtually useless. Today’s pistols often have front and rear sights at least a full tenth of an inch high, sometime 2 or 3 tenths high. This allows the eye of a stressed shooter to use them to acquire a good sight picture before shooting.

There have been many changes in handgun sight technology and handgun shooting techniques since the 1920s. One of the biggest improvements has been in the arena of highly visible front sights, whether it be by inserting a miniature capsule filled with mildly radioactive Tritium gas, i.e., Trijicon sights) into the sight blades so they literally glow (even in the dark), or by the use of fiber optic technology in the form of colored light gathering fibers that collect ambient light and display it in the direction of the shooter, they are improvements.

So there I was looking at my little M51 and bemoaning that the poor sights Remington attached to it made it obsolete before it’s time. Then I suddenly realized the top of the pistol’s slide, like the Walther PPK was machined by Remington essentially flat. As flat as the barrel rib of many shotguns, for which many forms of fiber optic sights are readily available. In as much as I own several different makes of shotguns and had acquired several different makes and colors of Fiber Optic front sights for them to replace the factory bead, I suddenly remembered I had a good assortment of them and one or two of them might even be appropriate in size for the top of the M-51 slide. I began to paw through my selection and quickly found one (I had acquired it at a Walmart) that seemed almost perfect.

Picture of the Fiber Optic front sight located in my collection of Fiber Optic sights.

The sight is short in length, about the size of a full .380 cartridge and only about 0.15″ high.

Picture of the Fiber Optic front sight adjacent to a .380 Silver-tip cartridge

Excited about the possibility of modernizing the M-51 I considered the problem of how to attach the front sight in a manner that would not destroy the collector value of the pistol. Being almost 100 years old and with only a fairly small production run the M-51 is a rarely seen pistol and prized by many collectors. Clearly vandalizing this fine pistol by drilling and tapping tiny screw holes into the pistol’s slide would depreciate the collector value of the piece. This also discarded TIG welding as the method of mounting. I have magnetic mounts for fiber optic sights, but on shotguns I have learned sometimes they stay in place on the shotgun when firing the shotgun, but also sometimes they simply fly off and vanish. For a usable self-defense pistol something more durable and stable in attachment was needed.

Glue was considered and rejected as glue quickly degrades with time and changes in atmospheric moisture. Also gun cleaning solvents tend to wash away many glues. No, I needed something glue like that was impervious to gun cleaning solvents and strong enough so that it would hold the front sight in position through hundreds of fired rounds and years of carrying.

Only one product I know of fit the bill. Sold only by Brownell’s, it is an epoxy intended for guns and called Acraglas. Most commonly used as a rifle bedding compound I just happened to have some left over from my last rifle bedding project. I mixed up a tiny batch into a paper bowl (back yard barbecue left-over). I then disassembled the pistol and with the sides of the side protected by some old towels, clamped the slide into a vise and using Q-tips I carefully applied some to the top of the pistol slide just behind the factory front sight.

Top of the M51 pistol slide, front sight area

Very carefully I then positioned the fiber optic sight assembly so that it as dead center left to right on the slide with it’s front just behind the factory front sight and the rear aligned with the factory rear sight. I let the Acraglas set up and dry over night.

Front sight positioning

The new front sight is a little taller, a full tenth of an inch taller.

profile photo of new front sight behind the factory front sight.

Currently being taught as a combat shooting technique is focus on the front sight. That technique is virtually impossible with the factory M-51 sight, especially in dim light. Not so with the new fiber optic sight. It practically glows like a miniature light bulb. Added to the natural pointability of the M51’s frame sight acquisition is very fast. .

Two pictures of the sight picture now that the Fiber Optic sight is installed.



I test fired the pistol both slow and rapid fire and the sight stayed in place and the groups at 21 feet (7 yards) were more than acceptable for a pocket pistol of this type and intended use.

This group is about a 3 inch spread. It would be less if not for the two fliers.


My M-51 has joined the 21st century.

One issue with an 87 year old ‘pocket’ pistol, is who makes a decent holster for it today? Well fortunately I do know some friendly gun dealers who were also curious about what kind of holster fits a Remington Model 51, so we spent about a half hour opening boxes and letting the M-51 try on different holsters before we finally found a good match. A company called Blackhawk makes an outside the pants nylon cordura hip holster which fits my Remington M-51 quite well. The holster is their size 1 3″-4″ Barrel Medium Auto holster. It is available in both right and left hand models.

Here is my own Remington M-51 in it’s new Blackhawk holster.


The Blackhawk product code for this holster is 73NH01BK-R (or L for left handed). If you owned an M-51 and want a holster for it, you could go to the Blackhawk website and look up on their website the location of a store near you that carries their products. Or you could simply click on this link below and simply buy one direct online from this Ebay vendor.

Blackhawk Holster for Remington M-51 pistol

Of course even with these little pocket pistols, practice is one of the primary keys to surviving the day you have to use it. It usually takes a minimum of 200 rounds with any pistol before proficiency is acquired. That means buying ammo in bulk. One supplier I am looking at is
AmmunitionDepot which today has a 350 round ‘gift box’ of .380 ammunition for only $149.97 plus shipping.

250 Rounds of PMC .380 ACP 90 Grain FMJ and
100 Rounds of Sig Sauer .380 ACP 90 Grain Elite V-Crown Hollow Point Ammo
for a 350 round total.

Where can you get Acraglas? That’s easy, go to

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