Sunday, August 2, 2015

How do Firing Mechanisms Work - II

In our last post, we saw a movie showing how a firearm could implement a mechanism to shoot in semi-automatic and full automatic modes. Of course, the video showed one particular way to achieve this, but there are other ways as well.

In today's post, we will study another mode of firing: burst mode. Burst mode is an intermediate between semi-automatic and full automatic firing modes. In semi-automatic mode, the weapon will fire one round per trigger pull and the user has to release and pull the trigger again to fire the next shot. In full automatic mode, the weapon will continue to fire automatically as long as the trigger is held down and there is ammunition available in the magazine. While full automatic firing provides a lot more firepower than firing in semi-automatic mode, it also tends to waste a lot more ammunition, especially if soldiers are inexperienced and hold down on the trigger for longer than necessary. The recoil from firing in full automatic mode also leads to inaccuracies. Burst mode provides a compromise between these two firing modes. When a firearm selector is set to fire in burst mode, it will fire up to a set number of rounds (usually 2 or 3 rounds) per trigger pull. After that, the user has to release and pull the trigger again to fire the next set of rounds and so on.

In Vietnam, the US military found that new soldiers often ran out of ammunition in combat, because they had set their M16 rifles in full automatic mode and shot their entire supply of ammunition in a few seconds (and often without hitting their targets). Therefore, they requested that the M16A2 model remove the full automatic mode option and implement a burst mode instead. Their studies showed that a three-round burst provides the best balance between firepower, accuracy and conservation of ammunition. This is why the M16A2 and M16A4 models and the M4 carbine models have a three-round burst mode.

A person named "Stealth the Unknown" has prepared a great video showing how these different firing modes were implemented on the M16 family of rifles:


In the case of M16 models, the burst mode is implemented by a rotating cam. The same video also describes how the mechanism works for semi-automatic and full automatic modes.

The same author also prepared a second video answering some follow-up questions about this mechanism.


For instance, in a M16, if the user releases the trigger before a three round burst is complete, then the next trigger pull will only fire 1 or 2 rounds. This is because the M16's cam mechanism does not reset when the trigger is released. In some other firearms, the mechanism resets every time the trigger is released and therefore the next trigger pull will fire the full number of rounds. The author of the video also goes into an interesting theoretical design where he designed a selector with multiple burst firing modes as well as a semi-automatic and full automatic modes.

Happy viewing.


Saturday, August 1, 2015

How do Firing Mechanisms Work - I

Hello everyone, I'm back from my long vacation and it was simply awesome. I'll publish some pictures of firearms that I took while I was visiting various places in Europe in a few days, after I do some editing. Until that happens, let's study how various firing mechanisms work, with the aid of some movies.

In today's post, we will look at an interesting movie about how semi-automatic and fully automatic weapons work. This movie was prepared by the US Army for training purposes sometime around the World War II period.


Note that this film depicts one way to achieve semi-automatic and fully-automatic fire. There are also other mechanisms, which we will study in subsequent posts.

Until then, happy viewing!


Saturday, July 11, 2015

Off For a Few Weeks

To the faithful readers of this blog... I'll be heading off to Europe on a much-needed vacation for a few weeks. Fear not though, I plan to carry my camera when visiting museums and historic sights and perhaps I'll find something interesting to talk about. See you guys and gals next month!

Friday, July 3, 2015

Handgun Shooting Analysis

In today's post, we will study the causes for inaccuracies when people shoot handguns. There is a handgun shooters chart, that helps shooters analyze what they are doing wrong. There are various variations of the same chart, but here's one public domain version, as designed by the US Army Marksmanship Unit.

Handgun Shooting Analysis chart, courtesy US Army Marksmanship Unit. Public domain image.


The above chart is designed for a right handed shooter. For a left handed shooter, the chart is mirrored vertically (e.g.) "Thumbing" is on the left, "Finger not on trigger correctly" is on the right etc.

The chart is pretty self-explanatory. For instance, if a right handed shooter is shooting too much to the left of the target, he or she is not placing the finger on the trigger correctly. However, some of these terms may need some explanation, so we will study those below.

Thumbing: When the shooter is squeezing the trigger, he or she pushes the right thumb and/or left thumb against the side of the frame, causing the front of the handgun to aim to the right (for a right-handed shooter. A left handed shooter will push the front of the handgun to the left). This causes the shots to end up to the right of the target.

Tightening grip when pulling the trigger: The shooter is tightening their hands along the grip, as the trigger is being squeezed. This causes the front of the gun to dip low and to the right.

Breaking wrist: This is caused because the shooter anticipates the recoil of the gun and does not lock the strong wrist properly. If the shooter tries to mimic the recoil, he or she breaks the wrists upward and shoots above the target. If the shooter tries to counteract the recoil, he or she breaks the wrists downward and the gun fires below the target.

Jerking: This happens when the shooter tries to fire the trigger as soon as the moving sights cross the target, adding excessive pressure to the trigger. This causes shots to end up low and to the left of the target.

Finger not on trigger correctly: This is caused when there is too little finger on the trigger. The trigger finger should cause the trigger to pull straight backwards. However, if there is too little finger area on the trigger, it will pull the trigger sideways and cause the shot to end up to the left of the target.

Pushing: This happens when the shooter jerks the trigger finger forward, just as the gun fires. The solution is to practice a proper follow-through and hold the gun steady during and after the trigger is pulled.

Heeling: This is caused by the shooter putting too much pressure with the heel of the hand, while the weapon is being fired.


Wednesday, July 1, 2015

Wacky Non-Functional Firearms

In today's post, we will look at an unusual object, something that is designed to look like a firearm, but actually isn't. We will look at something called a "scare pistol".

First, we will look at the origins of such a wacky invention. This class of "weapon" dates back to the 1880s. During this time period, the streets of Paris, France, were a dangerous place to be. Several criminals were roaming the streets and committing muggings and assaults, especially on women. Many women were urged to carry a small firearm with them, as a means of self-defense. However, some of these ladies did not wish to pull the trigger on another person. Seeing an opportunity, some French and Belgian manufacturers began to make "scare pistols" for these ladies.

A Scare Revolver from the 19th century. Public domain image.

The above looks like a commonly available Lefaucheux pinfire revolver model of that time period. This particular model is even made of brass and beautifully enameled and gold-plated. However, a closer look at the revolver reveals some interesting details. For one, the trigger cannot be pulled and is merely screwed on to the frame. The cylinder and hammer are non-functional as well. In fact, the only part of this so-called "revolver" that works or even moves, is the lanyard ring at the back of the handle!!

The idea behind manufacturing such a useless weapon was that even the sight of a firearm would be sufficient to scare off your average mugger (at least, that was the theory at that time). Therefore, for people who would hesitate to pull a trigger on another person, they could walk around with a non-functional, but realistic looking firearm.

The contents of a so-called "scare revolver" model. Public domain image.

In the above image, we have another so-called "scare pistol", Pulling back on the hammer causes this "revolver" to break at the cylinder. Inside is a mirror, a pair of functioning scissors, some needles, a thimble, two spools of thread and a crocheting hook. The front of the cylinder is a functioning pin-cushion and what looks like the shell extractor rod is actually a pencil. The butt of this "revolver" contains a small bottle to store perfume. This device is actually a scare revolver that also doubles as a functional sewing kit for carrying out minor repairs on clothes!


Monday, June 29, 2015

The Mad Minute

The next shooting sport we will look at is called the Mad Minute. It has its origins in a British Army exercise, which is described in a manual called "The Musketry Regulations, Part I, 1909).

The aim of this exercise is to demonstrate rapid fire shooting with good accuracy. The original exercise required the soldier to fire at an official "Second Class Figure" target, at a distance of 300 yards, using a Lee-Enfield service rifle and hit it at least 15 times within one minute.

A second class and first class target. Click on the image to enlarge.
Image taken from Musketry Regulations Part II. Public domain image.

The figure in the middle of the target is intended to resemble the silhouette of a man with a rifle peering out of a trench and measures about 12 inches x 12 inches. The next image shows a close up of the silhouette, including details of the actual colors used.

Details of the silhouette. Click on the image to enlarge. Public domain image.

As this was before World War I, notice that the silhouette resembles a man wearing a cloth cap.

A Lee-Enfield Mark I rifle. Click on the image to enlarge.

The soldier was allowed to load the rifle with one cartridge in the chamber and four in the magazine and get into the prone position. The target would then appear at a distance of 300 yards and the soldier would be expected to shoot with it. Reloading was allowed in groups of five cartridges from a pouch or bandoleer and the total time of the exercise was one minute. 

As long as the target was hit anywhere with a bullet, that counted as a hit. However, points were scored as follows: hitting the silhouette scored 4 points, hitting inside the inner ring scored 3 points, hitting inside the outer ring scored two points. Soldiers would be classified based on their accuracy, as marksmen, first-class shot, second-class shot and third-class shot. This exercise was one of a set of training exercises to grade soldiers. People who scored enough points to be classified as "marksmen" were given extra pay and a special crossed-rifles badge.

While the exercise only required 15 hits on target within a minute, many people would continue to fire even after 15 hits, to see how many times they could hit the target within that one minute. The smooth operation of the Lee-Enfield rifle's bolt action allowed soldiers to fire rapidly and accurately. Several people in the British Army could hit the target over 30 times within this time period! There are records of soldiers in the British Army scoring 36 or 38 hits within a minute at 300 yards.

By the time World War I started, the average British soldier was a better shot than his French or German counterpart. During the Battle of Mons, several German units reported that they were facing British troops armed with machine guns, when in reality, it was groups of riflemen firing rapidly using their bolt-action Lee-Enfield rifles.

These days, while this exercise is no longer part of military training, some people still organize "mad minute" competitions to see how many hits can be scored in a minute.


Tuesday, June 23, 2015

Three Gun Competitions

In our last couple of articles, we studied some sports where shooting formed a part, but those sports also involved other activities (running, skiing etc.) In today's post, we will study a sport where shooting forms a larger component. This sport is not an Olympic sport unlike the other two we studied before, but is popular in North America. We are talking about the three gun competition, otherwise spelled as 3-gun competition.

In the 19th and most of the 20th century, shooting competitions generally meant people were in fixed positions and shooting at targets with a single weapon. In these competitions, sometimes the targets are at a fixed known distance (e.g. pistol shooting, rifle shooting, biathlon, pentathlon etc.) and sometimes the targets move (e.g. trap shooting, skeet shooting etc.) However, the user stays in a fixed position and shoots at the targets. In some of these shooting events, e.g. pistol shooting or rifle shooting, time is not considered a huge factor (as long as the shooter stays below some fixed time limit). Reloading time also is not considered in these events and people generally have plenty of time to reload. Target types also stay the same throughout the competition (e.g.) pistol shooters always shoot at paper targets, trap shooters always shoot at clay targets etc. Another point about shooting competitions like this is that people generally become good at one type of firearm (e.g.) pistol, but aren't so good at using another firearm type (e.g.) rifle.

World famous shooter Jerry Miculek walking through a 3-gun course.

Three-gun competitions are a newer type of shooting competition that was started in 1980 by Soldier of Fortune magazine and gained popularity in America soon afterwards. Unlike the other competitions, the three gun competition is designed to simulate combat or self-defense scenarios. Shooters are expected to use three types of firearms in this type of competition:
  1. A handgun (pistol or revolver)
  2. A shotgun 
  3. A semi-automatic rifle.
Shooters proceed through an obstacle course and shoot at a variety of targets along the course, using different firearms at different stages through the course. The targets are all at varying distances from 1 meter to 500 meters or so, and are a variety of types (clay targets, paper targets, steel targets, empty cans, silhouettes, moving targets etc.). Shooters also engage these targets in a variety of positions (standing, kneeling, prone etc.) Shooters also carry firearms, holsters, spare magazines and ammunition with them and load and unload magazines as they proceed through the course. There are some rules such as the minimum calibers that can be used (handguns must use at least 9x19 mm. cartridges, rifles must use at least 5.45x39 mm. cartridges, shotguns must be larger than 20 gauge), types of sights, types of stocks, magazine capacity limit etc. but any firearm that meets the minimum requirements is allowed. Targets also have different zones that score more points if hit. In addition, if a heavier bullet is used, then more points are awarded for some targets, on the grounds that a competitor using a heavier recoil weapon isn't at a disadvantage against someone using a firearm with little recoil (in many competitions, .223 and 9 mm. are considered minor calibers and score less, whereas anything over .308 or .45 ACP are considered major calibers and score more for hits). In addition, unlike other shooting competitions, 3-gun competitions also feature targets that are supposed to be ignored by the shooter.

Competitors score points by hitting targets in specific areas and lose points by hitting the "no-shoot" targets (e.g. hostages, friendly targets etc.). Competitors also lose points for procedural penalties, such as shooting too close or too far from the target, knocking overhead material over while crawling through a tunnel, not performing a mandatory reload, using the wrong firearm type at a target etc. The time taken to complete the course is also factored into the final score. Therefore, the winner is decided by a combination of fast time and shooting accuracy. Competitors may be disqualified for safety violations, such as accidental discharges or unsafe firearm handling.

For firearms, competitors generally use a 9 mm. or larger pistol for the handgun stages, an autoloading or pump-action shotgun (commonly 12 gauge) and an AR style semi-automatic rifle. There are various divisions of 3-gun competitions: Limited, Tactical, Heavy Metal (He Man), Open and Outlaw. The difference between these divisions is generally the types of equipment used. For instance, in limited division competitions (which is for entry-level shooters), the rifle is allowed an unmagnified red dot, whereas in the tactical division competitions, a magnified optic is allowed. For the heavy metal division, the rifle must be at least .308 (or 7.62x51 mm.) or larger, the shotgun must be at least 12 gauge and the handgun must be at least .45 ACP or larger, and all sights should be ordinary iron sights with no optics allowed. The different divisions allow poorer shooters with inferior equipment to participate in these events as well. The majority of shooters tend to participate in the tactical division of a 3-gun competition.

Here's a video from the National Shooting Sports Foundation, showing how the three-gun competitions work:


Courses for 3-gun competitions have to meet some basic minimum standards, but beyond that, they are pretty much left to the match organizers' imaginations. This is why every competition is different. In some places, competitors are generally given a few minutes to walk through a course to familiarize themselves and form a plan of how they are going to proceed through it. In other places, the courses may be run blind (i.e.) the shooters do not know what to expect beforehand. Some competitions feature multiple stages with different courses at every stage and people get bonus points for winning a stage or finishing near the top, therefore a person who did well on every stage, but did not win any one of them, can still end up winning the overall competition.

Here's a couple of videos by Mr. Nick Leghorn showing a competition with multiple stages.





Happy viewing