Which weapon has the most recoil

Recoil - a perceived quantity

The recoil is the contact force between the weapon and the shooter or mount and thus an interaction between these two components.

THE There is no recoil, not even in relation to a single weapon. The recoil is always different, because a wide variety of influencing factors have to be taken into account. In particular, this is the shooter who has the weapon more or less at the ready.

The trigger for this article was a video on the net in which a statement made me sit up and take notice. With semi-automatic machines, the telescopic sight should be struck backwards! This contradicts the common stipulation that telescopic sights are struck forward. Can that be true? After some research, it became clear to me that there is probably no answer to this question to be found on the Internet, because many authors limit themselves to a few basic physical relationships, present a simplified model and it is good. Some go into detail, even set up measuring equipment, but what exactly should the results bring us? Unfortunately, there is very little about that.

That moved me to get in touch with Marcel Tschannen, most of us already well known for his publications on ballistics and optics. In the following I try to give my findings from practice, research and this conversation in a form that brings us added value for practice.

pulse

The so-called recoil results from the impulse that the casing "transmits" to the shooter. The pulse describes the mechanical state of motion of an object. The heavier and faster an object moves, the greater the impulse, so it is the "force" that an object has. The impulse can be very fast and strong, but also long and rather weak, whereby the overall size of the impulse remains the same. The momentum is the area described by the force-time curve.

Basic concepts

In order to understand the phenomenon of kickback, it is advisable to consider two basic concepts, respectively. To look more closely at connections. The principle of Action and reaction as well as the subject Bearing point.

Action and reaction

In physics, every action is opposed to a reaction. There's a gun on one Concrete wall it doesn’t give a millimeter during the «recoil», the blow is short, violent and has a high force peak. The concrete wall experiences a great "kick back". The reaction of the wall, which allows no path and therefore no time, determines the course of the impulse.

Is the same gun on a cocked one Rope by means of pulleys When hung up, the recoil does not react very strongly. The weapon is jolted and rolls backwards on the rope until the weapon comes to a standstill again due to the friction. The pulley experiences a very long «kickback».

The Sagittarius is neither a concrete wall nor a pulley, depending on weight, posture, muscle structure and position, he lies somewhere in between. The shooter is thus significantly involved in the phenomenon of recoil, can these resp. affect its expression.

The shooter can influence the reaction so significantly that, for example, a semi-automatic machine no longer charges. Some weapon malfunctions are due to this fact. The rifle housing is not rigidly connected to the bullet, the gases or the possible locking mechanism of a semi-automatic machine; here, too, there are interactions that significantly influence the impulse characteristics.

Bearing points

A precision rifle is well stored at the time of completion (blue arrows). It is supported on the shooter's shoulder, on the sandbag under the shaft and on the front of the bipod, and the shooter's head rests on the cheek rest. All of these points can take over more or less forces in different directions. When fired, the repeater transfers the forces in the barrel axis into the housing. The escaping gases push the weapon forwards via the muzzle brake and, for example, downwards if the muzzle brake is designed asymmetrically.

If one of these points is missing or if you change it significantly, e.g. by holding the gun down by the fore-end or omitting the sandbag, the whole system also changes.

If you simplify the above model, you can clearly see why the rifle tends to flip up. There is a height difference Δh between the bearing point and the pulse direction (barrel or lock axis), which is caused in particular by the shaft, respectively. the point of the shaft that rests on the shoulder is influenced.

This Δh respectively. the resulting lever creates an angular momentum that causes the weapon to flip up.

At the beginning of the report we promised to put the whole thing into practice and therefore the first practical tips:

Tip 1: The more stable, direct and immobile I lie behind the weapon, the stronger the peak of force, but also the shorter the impulse on the time axis. So I'm like a gun carriage. If I lie diagonally behind the rifle, I can bring the power tip down, because of my 80kg, for example, only 20kg are directly behind the system. With this I can reduce the hard blow, but the impulse remains the same, it then becomes a longer “thump” feeling. The weapon also has more time to move and in the worst case I push the weapon sideways into the target if I don't have a “natural point of aim”.

Tip 2: Thicker clothing or a softer shoulder pad gives the impulse more time and this also reduces the force peak. Again, the gun has more time to move.

Tip 3: The following statement can be made somewhat simplified - mount the telescopic sight high enough! The deeper the ZF, the deeper the cheek rest and the head, and the deeper the shoulder. This means that the point of support of the shoulder is well below the barrel axis, resulting in a greater lever. Since it is irrelevant for long-range shooters whether the scope is one or two cm further up, the shoulder support point (bearing) must be in the barrel axis as far as possible! This tip is used to reduce the stroke, so keep the weapon on the target.

Tip 4: In this simple system of a bolt action rifle or a shotgun, the rifle scope must always be aimed forward.

Tip 5: If the support is hard like glass, e.g. on the bipod or at the back of the stock, the rifle can jump open more clearly (knocking up), a softer base dampens this somewhat. For example, a long sandbag that can be placed under the bipod is ideal. “Load the bipod” also stabilizes.

Tip 6: Mass makes sluggish, applies not only to the shooter but also to the rifle. A heavy rifle remains calmer due to the greater inertia.

Tip 7: A muzzle brake or a silencer is an effective means of optimizing the perceived recoil on a repeater.

Tip 8: The unclean retraction of the weapon resp. the different recoil that results from it influences the muzzle velocity. This leads to precision problems.

We are actually through with precision shooting, if it weren't for the statement mentioned at the beginning that the ZF should be struck backwards in semi-automatic machines. Well, that may or may not be correct!

Self-loading systems

Systems that are self-loading, i.e. have a movable bolt, are immensely more complex than a simple precision rifle. And that's why we're now going into the details. Roughly speaking, one speaks of two different systems during the firing process:

The storey resp. Charge impulse occurs immediately after the launch and is not perceived as a single event by the shooter. We do not deal with the subject of ignition delay time in detail. The point here is that the projectile does not accelerate evenly, but can come to a standstill again when entering the trains and while running.

The housing and the barrel of a statically locked weapon (all except the ground lock) begin to move at the same time as the projectile. If the firing unit is inadequately connected to the load-bearing unit (shaft), it slaps around, with the bullet still in the barrel, and this results in enormous dispersion. That is why a clean bedding and tightened screws are so important. In the case of light revolvers for strong calibers, the muzzle rises before the bullet is out of the barrel and high shots result.

Regarding self-loaders, it can be said that there are always 2-3 hits:

  • Backstop with projectile exit (only if statically locked)
  • Flip backwards when the lock turns to the housing
  • Strike forward when the shutter closes

The bullet leaves the barrel after 0.5 to 1.0 milliseconds (depending on the barrel length), which is before you experience the recoil. The aftereffect, i.e. the outflow of the gases, also follows immediately. With a muzzle brake, the rifle can now be pulled forward by deflecting the gases. The actually felt recoil can only be felt when, for example, the ground lock hits the back of the housing.

Tip 8: A muzzle brake can increase the wear and tear on a semi-automatic machine, as the deflected gases «push» the rifle forwards while the breech is moving backwards. This makes the impact of the lock on the housing all the harder (not the perceived recoil)

Now the characteristics of a recoil are very dependent on the system. Semi-automatic machines with a simple mass lock have an unlocked lock, the mass of which is so large that a more reliable shot is guaranteed and which is then opened by the gas pressure. The assault rifle 57 has a delayed mass lock, also called roller lock, in which two retractable rollers slightly delay this process. An assault rifle 90 has completely different characteristics, because it has a gas tube with a gas piston. The lock is statically locked and begins to move later than with the simple ground lock.

In the case of a statically locked semi-automatic machine, the housing will certainly receive a first impulse from the projectile and the bolt, which is turned forwards again, pushes itself off the shoulder, i.e. the recoil impulse is greater than that of the projectile in phases. Incidentally, measurements in Europe today are made with the so-called «Nato shoulder». Yes, there really is, a standard shoulder with sensors that should ensure the most realistic test conditions possible.

How hard the closure at the back, respectively. then hits the front again is very different depending on the system, with an AK-47 this happens very hard at the back and front, for example, so it may well be that the ZF should be hit backwards here. In practice this has to be determined experimentally. Unfortunately, a basic rule cannot be derived from this. From practice this is correct, for example, with an MP5, here it is best to hit the back. Nevertheless, we stick to our practical tip for shooting self-loaded ones from the magazine with bolt action rifles and semi-automatic machines.

Tip 9: In the case of semi-automatic machines or repeater, if the ammunition is not crimped, i.e. self-loaded, the cartridge may lengthen, which then leads to a reduction in precision and loading problems. The trigger is the rifle striking backwards. Due to the higher inertia, the bullet in the cartridge case is taken less with it than the lighter case and is slowly "knocked" out of the case.

With a simple mass lock, the lock moves much earlier than with a gas pressure charger, which actually works exactly like a repeater in the first phase. Only when the ball has passed the gas pipe openings in the gas pressure charger and the gases flow into the gas pipe is the closure pushed back. The lock carrier is pushed backwards by the gas piston. It unlocks the bolt head, which has to turn first. Then they run back together. For those who want to understand this exactly, the following animation is recommended: AK-47 - This is how a rifle works!  

Therefore, the images of the impulses from the shutter and the housing are quite different for the two systems.

The word “gas pressure charger” is deliberately put in brackets in the graphic above. In fact, the progression of the gas pressure charger would be a bit “crazy” than that of the translated mass breech, because the housing first gets a blow to the rear during the bullet passage (like the bolt action), followed immediately by a blow to the front (as a reaction to the acceleration of the bolt carrier ). These strokes follow each other so briefly that the sequence can hardly be represented and the overall result is a very similar course to that of the translated mass closure.

Tip 10: The shaft, the shaft and again the shaft! What is a well-known credo for over and under shotguns also applies to semi-automatic machines and precision rifles. The shaft geometry, length, angle, shoulder support point, carriage support, handle inclination, distance to the trigger, etc. Everything has to be right. The right stock also determines whether I can cope with the recoil of a rifle. If you don't believe that, we recommend shooting with an original carbine 11 without a rubber cap and stock extension. Have fun 😊.

In summary, it can be said that there are astonishingly many possibilities to change the perceived recoil and to influence the rifle, whereby the advantages and disadvantages of the change must be weighed. A particularly heavy weapon or the use of a muzzle brake not only have advantages, we have a muzzle brake and silencer own article written.

Many thanks to Marcel Tschannen from theB&T AG in Thun for the time and patience and to Tom von vprojects for the good exchange regarding the ZF stop.

Alfred, October 22, 2019, SMKSG