One of earliest attempts to capture energy from a cartridge to operate the action of a rifle grew from John M. Browning's observation of the movement of brush and dust near the muzzle when a rifle was fired. He rigged up a crude piece of metal just past the muzzle to capture that energy and with a series of levers and rods was able to eventually get what began as a lever action Winchester rifle to function as a crude semi-automatic rifle. Since then hundreds, if not thousands of inventors have worked on ways to accomplish the loading, firing, extraction, ejection, and reloading of a gun. Each has advantages and disadvantages in terms of reliability, weight, cost and ease of manufacture. From all these attempts, a few dozen achieved adoption as military arms. But of those, only one was declared to be "the greatest battle implement ever devised."

Like Browning, John C. Garand built a rifle to operate from the energy trapped behind the bullet as it left the muzzle. Garand designed parts that would attach to the muzzle of a rifle to "trap" or concentrate the gas and direct it into a cylinder underneath the barrel. The gas pressure in the cylinder would then push back a piston on the end of a rod which would operate other parts and cause the desired functions to take place. Collectors have given this design the descriptive name of "Gas Trap" Garand.

Springfield Armory made about 46,000 rifles between August 1937 and June 1940 with the "gas trap" parts on the end of barrels 22 inches long. This design was replaced with a "gas port" arrangement. The same basic cylinder was retained under barrel. However, the barrel was two inches longer and the gas flowed through a hole drilled in the bottom of the barrel about two inches from the muzzle. Thus the only practical difference was the means by which the gas entered the cylinder to begin the job of pushing the piston on the end of the rod to make the rest of the sequence happen. Of course, it was desired that our troops have the best equipment, and all of the same standard design to simplify training and support of weapons in the field. Therefore the "gas trap" rifles were altered as soon as possible to the new ‘gas port’ configuration.  Others can better explain the details of how the conversions were accomplished.

We can all speculate as to why some rifles never got updated. An oversimplified explanation is that some gas trap rifles had been sent to remote locations and never got returned. Some may have been misplaced or otherwise detoured from where they should have gone. One such rifle recently turned up in Alaska where the quasi-military force using them was told at the end of the war that they could just keep their rifles and whatever other equipment they had been issued. Another rifle was found in the rafters of an old WW2 barracks building at a remote Army post in Arizona. There are probably some more out there waiting for a lucky collector to find them.

The rifle examined here had been in the basement of a house in a small town in Utah for the last 50 years. It had been sent home from Japan in 1945 by a (now deceased) Army veteran. His family remembers him telling how he had been late getting to the place in Japan where captured Japanese arms were being distributed for American GIs to send home. We can only imagine his disappointment at not getting a nice Japanese Arisaka 7.7mm Type 99 rifle like the rest of his friends. However, he was allowed to send this rifle home, according to the family. There is a possibility that it was captured by the Japanese in the Philippines, or elsewhere early in the war, and thus found among the Japanese arms. There is also a possibility that the soldier had carried this rifle throughout the war, and shipped it home without authorization. We will probably never know for sure.

Many gun collectors would note that these "gas trap" rifles look strange, but probably not pay much attention to one seen at a distance. Garand collectors, however, would immediately note the distinctly different cylinder and "gas trap" arrangement. But since most of us never have a chance to take one apart, what will look different inside? And, does it come apart the same way? Let's find out!

Looking at the "gas trap" on the end of the rifle it would be logical to try to get it apart much the same as the familiar "gas port" rifles. Remove a screw and it is pretty obvious that the "plug" at the front will have to slide up to get it out of the cylinder. That works fine.
 
 
 
 
 
 
 
 
 
 
 

Now we would expect the gas cylinder to just slide off to the front. Having had to tap a little on tight fitting cylinders on the later rifles this seems a natural impulse. BUT, it is WRONG! It turns out that the barrel is threaded underneath the front sight so the gas cylinder has to be unscrewed off the barrel. Before you can do that, you must remove the screw holding the front sight and lift the sight up.  The "gas trap" sight fits down through a slot in the gas cylinder ring into a spline in the top of the barrel so it will line up properly.
 
 
 

The later gas port front sight was on a transverse dovetail making it unlikely that it would be lined up properly if it was loosened. This makes you think that maybe the seal over the front sight screw may have been there because troops were used to removing the front sight when cleaning their M1 rifles.
 
 
 
 
 

Examination of the "plug" shows that it fits tightly into the slot at the front of the gas cylinder and when fully inserted leaves an internal gap of about 1/16" between the face of the muzzle and the rear face of the plug. The front of the plug protrudes nearly two inches (with a hole through it carefully aligned with the bore). For the tiny period of time the bullet is making its way through the plug, the pressure of the gas behind it is very high, passing down behind the plug into the cylinder with sufficient pressure to force the piston and operating rod into motion
 
 
 
 
 

Note that the screws that hold the front sight and the plug in place have unusual tapered heads. The rear sight elevation knob screw is very similar, and some collectors have wondered about the odd head on that screw. Maybe it is odd because we see the orphan that is left on later rifles, not all three similar examples as found on the "gas trap."
 
 

Of course before you can remove the gas cylinder the operating rod and some other parts must be removed. The steps are the same as with the later rifles, but some of the parts are unusual.
 
 
 
 
 

The trigger housing group looks familiar, but should reveal differences on close inspection. The drawing number on the left side will probably show only the basic part number, without any revisions. The hole at the left rear is a round hole, not the later "cloverleaf" pattern.
 
 
 
 
 
 
 
 
 
 
 

From the right side we can see that the "pad" at the top rear of the trigger housing is almost square rather than a narrow rectangle shape, usually known as "large pad" or "small pad." respectively. The hammer has an extra hole in the middle, and is marked on the side instead on the front. The trigger has an extra hole (visible through the large hole in the support part of the trigger housing.) All these extra holes are probably related to steps in the manufacturing process, or to facilitate heat treatment or something. Most collectors will look lovingly at them and be glad they are there but not worry about the reason for them, just noting that the respected reference books by Scott Duff and others decree them to be "right." The safety is flat across much of the top instead of a graceful arc.
 
 
 
 
 
 
 

Upon removal of the action from the stock the spring(s) in the operating rod are obviously different, but disassembly is basically the same. The operating spring is shorter than on later rifles, and made with wire that is flat on the top.
 
 
 
 
 
 
 

This is known as a "keystone" spring because in cross section it has that shape more than the simple round wire used in the later springs. The follower rod has a round shaft instead of flat as on later rifles, but that is harder to see.
 
 
 
 
 

Really obvious is the "keystone" type spring fitting snugly on follower rod shaft. This is a "compensating spring" intended to dampen the forward motion of the operating rod. Later rifles used the single round wire operating spring instead of the two separate keystone springs.
 
 
 
 
 
 
 
 

The small parts have only small differences. Most obvious is the follower which is left bright, not parkerized or blued, and marked with a "2" on the bottom to indicate it was made in accordance with the second revision to the drawings for that part, and the "tail" is narrower than on later rifles. The angle on the rear of the follower slide is steeper. The follower arm has a single bevel.
 
 
 
 
 
 
 
 
 

The bullet guide is milled, and drawing number information is stamped near one end.
 
 
 
 
 
 
 
 
 
 
 

The operating rod is removed in the usual manner, and then the bolt. The drawing number is very large, taking up most of the width of the bolt, forcing the stamping of the revision number beneath it.. Around the middle of the bolt is a letter number marking showing the "heat lot" of steel used for the bolt. This was necessary in case it turned out that a bad batch of steel was causing parts to fail. The offending parts could be identified and replaced without having to replace every part ever made. There is no hole in the bottom of the bolt into the firing pin hole. If the bolt is disassembled, the firing pin will be round instead of flattened along the bottom of its length.
 
 
 
 
 
 
 
 
 
 
 
 
 

The rear of the receiver has the manufacturer and serial number information. Years of research in military records have produced documentation on many U.S. military arms, but probably only a small fraction of any one type. This is usually something recorded at some time such as assembled on a certain date, or shipped to a certain location or unit, a problem reported, stolen or recovered, sold, returned for repairs, inspected in the field for some reason. It is fascinating to collectors to be able to document even a single event in the history of a rifle. Perhaps it is the great rarity of such documentation that makes it so special. There is no known historical information on this rifle. Scott Duff's The M1 Garand: World War II does provide the approximate date of manufacture, in this case March 1940.
 
 
 
 
 
 
 

The rear sight cover spring has drawing numbers marked on it, and lacks the familiar ribs found on later rifles. The rear sight has a "short pinion" with no locking bar on the right (windage) side.
 
 
 
 
 
 
 
 
 
 

Even before the rifle is disassembled, it is obvious that the buttplate is a solid piece, without the familiar trap for cleaning equipment.
 
 
 
 
 
 
 

When the plate is removed, instead of two equal size holes for storage of cleaning gear we find one large hole and a smaller hole. These holes are just to reduce the weight of the rifle. When the butt trap was added for cleaning gear, the holes were made equal size, and some older stocks were modified.

Other stock differences include a pronounced "snout" protruding from the metal ferrule on the front of the upper handguard, and the lack of a small clearance cut at the right rear of the rear handguard. The barrel band between the handguards and the clip on the rear handguard are milled with a groove in the center.

Okay, these are the major difference you will find on a "gas trap" Garand. There are a few more minor details, and real fanatical collectors will further refine the "gas trap" rifles into at least two different sub categories.

After you find the first one you will become more interested in the rest of the details. I wish you luck. However, as Scott Duff pointed out after I found mine, "The harder you work, the luckier you get."