Just found out "hair trigger" is a real thing. In what situations is it used?

It’s a real thing, metaphorically, for asingle-set trigger:

A single set trigger is usually one trigger that may be fired with a conventional amount of trigger pull weight or may be “set” – usually by pushing forward on the trigger, or by pushing forward on a small lever attached to the rear of the trigger. This takes up the trigger slack (or otherwise called take-up) in the trigger and allows for a much lighter trigger pull. This is colloquially known as a hair trigger.

Is this setting–available on some pistols and not others–used in tactical situations? “Quick-draw” events?

The trigger pull for rifles and pistols can be set to be different from what the factory provides by a gunsmith. When the trigger pull is set low enough, say under 4 pounds, some call that a hair trigger.

Competitive target shooters generally like light trigger pulls.

This types of trigger (ordinary trigger that can be “set” to a hair trigger) is found primarily on European hunting rifles and some Euro target rifles. While somewhat popular up to the 1950’s, you don’t see them much anymore due to product liability issues.

Target shooting. When you pull a trigger, it’s easy to change your aim point, because you are changing your grip by moving your trigger finger. A light trigger makes it much easier to keep the gun on target.

There are also double set triggers. In those, there are two separate triggers. One trigger preforms the set, then a separate trigger that fires the gun. Like a single set trigger, the ‘working’ trigger can also fire the gun with a heavier pull (well, heavier than the set).

Huh. I was right about event-competitions–although Profound mentions rifles for hunting–but assumed it was a pistol-onlly thing.

You don’t have to be a gunsmith honestly. I own a pistol and hated the heavy pull required on it. The more you have to squeeze the trigger, the more difficult it is to keep your gun pointed at the target while in the process of firing it.

I bought a whole new assembly as a kit from an online seller and replaced a handful of parts. Not just in the trigger itself but also where the firing pin gets engaged.

I also installed a RAM (recoil assistance module) for a smoother action.

I was able to to this in my garage with a mallet and a special punch to knock out the pins holding the gun together. I followed a Youtube video.

My gun has a very light and smooth pull now, it used to “catch” halfway through which caused the gun to jerk slightly.

The only modification I’ve made to my gun which I had a gunsmith do is replace the original sights with glow-in-the-dark tritium sights. Getting sights aligned precisely is very difficult and I let a professional handle that bit.

One of the primary qualifications for guns is the quality of the trigger pull. Light and smooth is generally considered better. I have no idea why gun manufacturers don’t pay much more close attention to it. You shouldn’t have to buy one and have modifications made.

Well I’ve read (but have trouble confirming officially so maybe this is pro-gun hysteria or now obsolete) that Massachusetts and New York had trigger pull weight requirements; 10 lb in the case of Mass, no idea what NY’s is supposed to be. This doesn’t make a modified gun illegal to use or own, but dealers can’t sell them that way. I’m mainly finding references to these laws on forums for gun owners so this might not be accurate. But if it is, that might be a reason for manufacturers to produce them that way.

Once upon a time, this was a feature of some duelling pistols. Wouldn’t want to spoil your aim at the critical moment.

The New York Trigger-1(7.75-8#) and New York Trigger-2(11#) were/are a requirement for pistols issued by certain police departments to increase the weight of the standard trigger pull on Glock (5.5#) handguns. As was discovered during the transition from revolvers with long, heavy trigger pulls to the much lighter, smoother Glocks there was an increased chance for negligent discharge. This was exacerbated by the Glock’s lack of an external saftey and the then current habit of officers to keep their finger on the trigger even before wanting to shoot.
This had the unintended but foreseeable effect of making accurate shots far more difficult.

The NYPD mandated the heavier NY-2 while the NY state police the NY-2.

There was never any requirement for a minimum trigger pull for pistols sold to the general public, but as a matter of saftey, anything less than around 4 pounds is generally recommended for defensive carry.

Missed edit window
The last line should read: “generally NOT recommended for defensive carry.”

This is because of the increased chance of a negligent discharge, especially under stressful conditions.

The dueling pistols used in the Burr-Hamilton Duel could be set to hair-trigger. The guns belonged to Hamilton, and he had a record of firing first in multiple duels. In this case his gun went off early, while not aimed properly.

The guns belong to the Smithsonian, and were x-rayed and described in the 1970’s.

It is possible that Hamilton deliberately fired early and missed. It is also possible that using non-standard dueling pistols with a secret hair-trigger was cheating, and that he had been cheating all along. I’ve seen it argued both ways.

Related to target shooting, you could also use a light trigger pull in a sniper rifle or designated marksman rifle. The greater the trigger pull, the more time and asymmetrical pull on the gun. The most accurate trigger possible would be a button or a laser beam that authorizes firing the round when interrupted.

A few years back Savage developed their Accutrigger for rifles. It provides the safety of a heavier trigger pull reducing the chance or accidental discharge while still providing a reasonably light pull for accuracy. Other manufacturers have either licensed their design or developed their own version. Some allow pull weight adjustment by the user via a screw adjustment.

MichaelEmouse mentioned a switch to fire the shot. There have been target pistols marketed with this feature. I don’t know if any are still on the market.

Some of my target pistols have a pull weight of about 1 1/2 pounds. Not at all good for defensive carry.

Well, that was OP. Do they? Any production models out there?

Upthread mentioned only hunting rifles.

Remington EtronX: Electrically Primed Ammunition 2000-2003
From the video description.

Oh, I meant, in reply to Michael, “sniper or designated marksman rifle.”]

ETA: The video shows why electric rifles are a bad idea, outside Hollywood.

It’s likely that there eventually will be. The closest we currently have to that in small arms is the TrackingPoint rifle which works by tagging a target, having the computer in the fire control system computer the bullet’s trajectory using about dozen factors then firing only when 2 conditions are fulfilled at the same time: 1) The trigger is pulled 2) the barrel is point in a direction where, if the shot went off, it would likely hit the target.

In other words, in that firing mode, pulling the trigger only authorizes the computer to fire but isn’t sufficient to fire by itself. It’s reminiscent of the fire control computer of fighter aircraft guns or Continually Computed Release Point mode used for bombing.

More info: https://www.youtube.com/watch?v=Pmteh_NChOQ

Double-set triggers were an option, a triggr with a heavier pull unlocks a second trigger with a much lighter – as in an ounce or two – pull to touch off the round. Here is a clip from Quigley Down Under showing a double-set Sharps. Skip to 3:30 to see the second trigger being set.

Mmm, I’m not so sure about that, since you would know exactly when the round goes off. And if you know exactly when the round goes off, you will finch just beforehand.

In other words, there are those who say that - as you are applying pressure to the trigger - the precise moment the round goes off should be a surprise. That way, it’s impossible for you to flinch at the moment the round goes off. And as a result, they believe a good trigger should be designed with this goal in mind.