Nick demonstrates how the rifle trigger is squeezed off with the pad of the muscle between the first and second joint of the index finger.

Triggernometry’s the name of the game


49
57 shares, 49 points

Exercising trigger control is the essence of good shooting.

If the nut behind the butt manages to get his shot off when the gun is held steady, he is going to score a hit. If the gun is not held steady and is wobbling all over the place, he is not.

The shooter may miss for a number of reasons, he may flinch or jerk the trigger or he may close his eyes and yank the trigger (aspects of the same thing).

Many a standing deer has been missed at less than 50 metres by a recoil sensitive individual who is scared of his rifle and throws an involuntary flinch, or he may slow or stop his swing on running game.

The modern single-stage adjustable trigger is the product of long evolution that began when some genius with a matchlock decided that instead of having to apply a smoldering match to the touchhole by hand, he would put the burning match on the end of a lever and then by pressing the other end with his finger put the fire through the touchhole. This was the first trigger, crude though it may have been.

Since that time, ignition systems have changed and triggers along with them. There have been wheellocks, flintlocks and cap locks.

As anyone who has ever shot an old muzzle loader loaded with black powder and set-off by a flint can tell you, a considerable amount of time elapses between the release of the trigger and the bullet leaving the muzzle of the barrel.

During the past century, ignition time and lock time have become a lot faster. Modern rifles feature “speed locks” with lighter firing pins, shorter falls, and stronger springs which give faster ignition.

Lock time is much faster with actions like the Remington Model 700 Remington 2.6 – 3 milliseconds (m/s)and the Model 70 Winchester (3 m/s) than with the Mauser ‘98 5.2 m/s) or the M-17 Enfield (6.5 m/s).

The original Mannlicher-Schoenauer has the heavy cocking piece and safety hung on the firing pin, and pulling the trigger results in ignition as slow and ponderous as the dropping of a bucket full of nuts and bolts.

The total elapsed time required to fire a cartridge is taken up by three distinct intervals; trigger actuation to sear release, sear release to striker impact, and striker impact to exit of the bullet from the muzzle.

The first two are combined and referred to as lock time, while the third is termed action time, despite the fact that it is really a combination of ignition/ barrel times.

Lock time is purely a mechanical function; action time on the other hand, involves the ammunition and barrel. As a rule it runs from 1.5 to 1.5 m/s, while lock time in a bolt action generally runs between 2 and 9m/s.

For lever, pumps and automatics, which have non-straightline systems, lock time can be considerably greater. Lock time is governed largely by the length of firing pin travel, the power of the mainspring, and the weight the mainspring must accelerate.

Obviously, the faster the lock time of your rifle, the less time there is to allow your aim to wobble off the target.

Various adjectives are used to describe good trigger pulls. They are called clean, crisp and totally inert. It is often said that they let off like the breaking of a glass rod, meaning there’s a complete lack of any creep or backlash. Bad trigger pulls are called draggy, creepy, grating.

The perfect trigger pull is difficult to describe, but whether on rifle, shotgun, or handgun, it should let off at the same pressure each time and break cleanly.

A lot of shooters like very light pulls – or imagine they do – until they find they cannot exercise full control over them. On a bolt-action rifle for big game, you want to be able to “feel” the trigger.

A clean, crisp pull that lets off at 1.36kgs (3lbs) is just about ideal for a hunting rifle. Pulls much lighter than .097 kgs (2 lbs) are too light to be entirely safe, and also often too light to give the rifleman complete control. Thus, he cannot hope to “call his shots.”

Simonpure varminters are well served by a pull of around 0.907 kgs (2lbs) which is plenty light enough to allow precise shooting at small targets at long range. Much lighter than this and you’ll find that too many shots get away from you. By that I mean that quite often the rifles go off before you intend them to, allowing the shot to go wide.

The worst kind of trigger is one that’s both light and creepy and never goes off twice at the same pull. It’s a miserable pull for shooting offand or sitting since you have no earthly idea of when it is likely to go off.

Such pulls often come about on sporting rifles when some amateur gunsmith makes a bungling attempt to alter them. He files or stones the contact surfaces of sear and cocking piece often removing their surface hardness. These surfaces should be smooth and flat, but poor work with a stone leaves them rough and grooved, resulting in a pull that’s uncertain and creepy.

Various kinds of “set” triggers are made. Germanic hunters seem to like the “double set” variety where the rear trigger is pulled back to “set” the mechanism so that the slightest pressure on the front trigger lets the firing pin fall.

Today, companies like CZ equip their rifles with “single set” triggers which are set by simply pressing the trigger forward. It then goes off with anything from a hard look to a sneeze.

Unset these rifles can be adjusted to have a good, crisp single-stage pull, so experienced hunters seldom bother to use them set.

For the practical hunter-rifleman set triggers are inconvenient on a hunting rifle. Most of the time the hunter doesn’t have time to set his trigger when he sees game, especially if he jumps an animal from its bed.

Although there be some merit to having a lighter let-off when game is spotted feeding undisturbed and a long way off. In this kind of situation, the hunter has plenty of time to lie down, take a steady rest and set the trigger before he touches old Betsy off.

Most bolt action military rifles have double-stage pulls. There is a preliminary pull during which the trigger moves back a short distance against the tension of the sear spring.

On a properly-adjusted double-stage trigger about 0.68 kgs to 0.907kg of pressure is necessary to pull off the first stage. After that the pull should be clean and crisp.

A rifleman familiar with such a pull learns to take up the first stage without thinking as he raises the rifle to his shoulder. He then squeezes out the second stage and gun goes off.

Double-stage pulls on some modern rifles like the Ruger M77 and Anschutz rifles, are very sweet, but most shooters don’t like them, showing a distinct preference for the crisp single-stage pulls found on the vast majority of modern sporters.

Timney makes excellent replacement trigger mechanisms for installation on ex-military Mauser, Enfield and Springfield rifles as well as those modern rifles with non-adjustable triggers.

These give crisp, single-stage pulls and are adjustable for weight of pull, As well as the Timney Drop-In trigger modules, mechanisms made by Jewell are adjustable from 43 grams to 1.81 kgs.

A good trigger is necessary when shooting a rifle from the least steady field positions, but you should know exactly when the musket if going to go off. Try to squeeze out all except the last few grams of the pull, and then when the sights look right, try to squeeze out the balance smoothly and quickly without disturbing the aim.

This method calls for self control and a delicate touch. The shooter must be able to call every shot. If it isn’t where he called it, he has either flinched or wobbled off the target.

With a rifle you gain the best control of the trigger when you squeeze with the pad of muscle between the first and second joint of the index finger.

A nicely curved pistol grip that is not too sharply curved or too close to the trigger finger makes it easier for three fingers to hold the butt firmly against the shoulder and the index finger free to press the trigger.

Trigger control becomes part of the subconscious so that the experienced shooter knows under hunting conditions exactly when his gun is going to go off. But trigger control becomes automatic only after years of practice and by firing thousands of shots.

The trigger mechanism is a very small part of the firearm, but how it is adjusted and how the shooter handles it is very important. Use it to get off the shot at the right time and you’ll hit, but touch it off at the wrong time and the wrong way and you’ll score a miss. ?

 

This article was first published in the June 2014 issue of Sporting Shooter magazine.

 


Like it? Share with your friends!

49
57 shares, 49 points

What's Your Reaction?

super super
10
super
fail fail
4
fail
fun fun
2
fun
bad bad
20
bad
hate hate
18
hate
lol lol
16
lol
love love
14
love
omg omg
10
omg

0 Comments

Send this to a friend