Patent Application
20110252686
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The present invention relates to an improved extractor depressor plunger assembly for use in handguns. More particularly, the present invention is a high reliability extractor depressor assembly that is designed to significantly increase reliability in harsh or extreme environments and/or in heavy usage.
While the claimed high reliability extractor depressor assembly can be used effectively in many different types of handguns, for the purposes of explaining the attributes of the invention, a Glock 17 will be used as the demonstration platform.
Handguns are well known and disclosed in the prior art. In most handguns, the extractor depressor assembly is well known and mature technology. The primary feature of this design is having the majority of the mass forward of the extractor depressor plunger spring (i.e. towards the muzzle). While this has served the various Glock models well in the past, it has occasionally led to performance problems in severe environments on in heavy use.
The prior art teaches several distinct types of handguns and in particular several types of Glocks.
U.S. Pat. No. 4,539,889 to Gaston Glock teaches a standard Glock pistol with a conventional extractor depressor mechanism.
Similarly, U.S. Pat. No. 4,825,744 also to Gaston Glock discloses a Glock pistol with a conventional extractor depressor mechanism.
The above cited examples of the prior art comprise a standard extractor depressor assembly as is shown in
The present invention is directed toward a high reliability extractor depressor assembly that is designed to significantly increase reliability in harsh or extreme environments and/or in heavy usage. This is accomplished by redesigning the extractor depressor assembly to include higher mass, an optimized redistributed balance that results in greater and, most importantly, more consistent extractor tension, nominally less recoil, and somewhat improved friction wear.
The instant invention refers to a redesigned and improved high reliability extractor depressor assembly for a handgun. For ease in understanding the instant invention will be described in the context of a Glock 17.
In order to understand and appreciate the significant benefits of the instant invention, it is instructive to review the function of current extractor depressor plunger assemblies in relation to other parts of a Glock. In a standard or stock Glock, once the gun has been “fired”, and the bullet and propellant gases have exited the barrel, the slide begins to decelerate. This deceleration causes free mass components in the slide (for example, the extractor assembly, firing pin, etc.) to exert rearward pressure on the slide. Said another way, as the slide decelerates, free masses in the slide will press against the rear of the slide just as a person riding in a vehicle presses against his or her seatbelt during sudden braking.
In the standard Glock, the deceleration of the slide causes de-loading of the extractor. Essentially, the deloading occurs as the weight/mass of the extractor depressor plunger exerts force to the rear as the slide decelerates. The resulting force is in opposition to the spring and results in less pressure on the extractor. The deceleration in a recoiling firearm is not generally smooth and tends to sharpen at several key points prior to extraction:
At each of these points, any mass forward of the extractor spring will apply compressive force (rearward force) to the spring and reduce the pressure on the extractor. Variations in extractor pressure increase the likelihood of the extractor jumping over the rim of the cartridge and leaving the cartridge in the chamber—failure to extract. The extractor is basically a hook that grabs onto the rim of the cartridge. Pressure on the extractor maintains the hook in place. If pressure is reduced just as the cartridge is extracted the extractor may not stay in place. In other words, the mass of the extractor depressor is thrown toward the rear of the firearm away from the extractor as the slide decelerates. As there are significant G forces involved, the mass of the extractor depressor is multiplied many times. It is for this reason that it is critical to keep the mass forward of the spring relatively low.
This compressive force on the extractor spring is further exacerbated by anything that increases the frame's resistance to movement as this increases the rate of deceleration in the slide. Put simply, the harder the frame is to move the more quickly the slide will come to a stop. This means the addition of mass such as tactical lights or metal guide-rods all reduce extractor effectiveness. The effect is also more pronounced with very experienced shooters who take a very high, very firm grip on the weapon. The effect is more pronounced for aftermarket metal frames which tend to have different characteristics than stock frames, or with the addition of tactical lights.
In semi-automatic firearms, the extractor serves to latch onto and remove the shell casing from the chamber after firing. In designs such as the Glock the extractor is a claw-like catch that hooks into a depression in the base of the cartridge and pulls the round out of the chamber. Generally, there is a spring (or springs) that provides the tension to keep the extractor claw in the groove of the cartridge. If there is insufficient pressure on the extractor to keep it in the groove of the cartridge the extractor will slip off of the cartridge rather than pulling it free from the chamber. This is what is generally known as a “failure to extract” malfunction or FTE. As extraction takes place during recoil it is important that the violent recoil of the firearm does not inadvertently reduce the pressure on the extractor when it is needed most. Additionally, as extractors are typically spring powered it is important that they are designed to reduce their tendency to ‘bounce’ and loose contact with the cartridge.
The present invention improves the performance of the Glock by significantly reducing the effect of recoil on the extractor depressor plunger assembly. These positive effects are accomplished by the following:
A. designing a new longer piece (standoff bar) of greater mass.
B. redistributing the mass from the front of the assembly to the rear.
C. designing a new shorter piece (extractor depressor plunger).
D. increasing total mass of the assembly.
The attributes of these redesigned components will be discussed in the following sections.
Referring to
At this point, it is instructive to describe the mechanics of the extraction process. When the slide first begins to accelerate toward the rear, the mass of the entire extractor depressor plunger assembly bears forward against the extractor. Ideally, you want an extremely heavy assembly when the slide is accelerating to the rear to maximize seating pressure on the extractor. However, when the slide starts to decelerate while moving to the rear, that same mass works the other way and tries to move away from the extractor. To counter this, the design of the instant invention moves the majority of the mass rearward of the spring.
In order to better understand this concept, it is instructive to think of a person riding in a car attempting to keep pressure against the backrest of the seat on which he or she is sitting during acceleration, normal at speed travel, and heavy braking. In this analogy the backrest represents the extractor where we want pressure applied. When the car accelerates a person's mass helps push them against the backrest. Applying this analogy to a standard Glock there is a spring in front of the person (between them and the dash) helping to keep pressure against the back of the seat. This works fine while accelerating. However, the situation is somewhat different when the brakes are applied heavily (or “slammed”). When the brakes are slammed, the person's weight presses forward and compresses the spring, which takes pressure off of the backrest behind them. Even if the seatbelt stops their forward movement they may have already moved far enough forward that their back is no longer touching the backrest behind them. Similarly, once the gun is fired, the forces inherent to the firing process would tend to relieve pressure on the extractor and cause the mechanism to become unstable and more susceptible to jamming and instability. The present design differs from the standard design in that the spring is located behind the person (between their back and the seat) rather than in front of them. In this case when the car accelerates the weight of the person helps push the spring more firmly into the back of the seat, so during acceleration this works just as well as the typical design. However, when the brakes are slammed with the spring located between the backrest and person's back, the spring will continue to apply pressure to the backrest even if the person leans forward into the seatbelt. In the standard design the mass of the person beneficial during acceleration, but a detriment during deceleration, so a compromise of lighter mass is generally used. With the present design the person's mass remains a benefit during acceleration, but has no negative effect during deceleration. As a result, a higher mass can be used to maximize the benefit during acceleration.
Referring to
A. the length of the bearing nose 46 was increased slightly to provide greater resistance to canting.
B. The spring retention section 48 of the bearing spring guide was widened. This geometry ensures that the first coil of the spring which is wound around the bearing has a slightly greater diameter than the bearing diameter. As a result the first coil of the spring makes solid contact with the raceway. This effectively lengthens the nose of the bearing (reducing canting) without adding mass. This also shields the sharp edge of the bearing seat from the raceway.
C. the bearing seat 47 was slightly back cut to reduce any gap and improve fit between the spring seat and the spring itself. This is done to reduce the likelihood of binding in the raceway.
D. finally, the geometry of the spring guide 42 was designed to limit canting to approximately 1 degree, so even if other measures fail, the spring itself will hold the bearing in the proper position.
Perhaps the most significant improvement of improved extractor depressor plunger assembly is the mass distribution of the new assembly with respect to the stock assembly. Whereas the stock assembly has the longer (high mass) component forward (towards the muzzle) of the actuating spring and the shorter (low-mass) component to the rear of the spring, the improved extractor depressor plunger assembly has the long component to the rear of the spring and the shorter piece toward the front.
The approximate size and geometry of the various components in the present invention are as follows:
The standoff bar can be made of any strong rigid material with a high density, good heat tolerance and galvanic compatibility with the rest of the firearm. The spring can be made of stainless steel, various carbon steels, titanium, or composite with the preferred material being stainless steel. Finally, the plunger can be made of any strong hard material with good heat and abrasion resistance with a martensitic grade of stainless steel being the preferred material.
