Gun Digest

Self Defense: When A Trigger Upgrade Becomes A “Hair Trigger”

Any modification done to lighten the pull of a trigger is likely to become a "hair trigger" in court.
Any modification done to lighten the pull of a trigger is likely to become a “hair trigger” in court.

Is a trigger upgrade on your self-defense handgun worth it? Not when politically motivated prosecutors are likely to twist it into the mythical “hair trigger”.

Avoid trigger pulls lighter than factory specifications for duty guns. Jargon alert here: when I say “duty guns,” I mean firearms intended for police/military service or self-defense as opposed to target handguns. “Factory spec” means the specifications of the manufacturer of the firearm itself, not the company that made the drop-in aftermarket trigger kit.

There are two definitions of “hair trigger,” either or both of which can come up in court. One is “lighter than factory spec,” and the other is “different from common custom and practice among those who use such machines daily.” The same, really, as if there had been an industrial accident or a car crash involving machines that were alleged to have been negligently adjusted, injury or death resulting.

This can come from an unintended discharge, but what a lot of people miss in the gun world is, it can also come from a false allegation of a negligent discharge.

Why would a prosecutor allege that you fired unintentionally when you in fact deliberately used your gun to save your life? If it’s a politically motivated prosecution, it’s because an established case of self-defense is what’s known in court as a “perfect defense,” but there’s no such thing as a “justifiable accident” or “accidental self-defense.” You won’t be getting any gun experts on your jury, you’ll be getting a dozen or so people selected by the accusing side for their lack of knowledge of firearms and self-defense law and tactics. Opposing lawyers know it’s a lot easier to convince a jury of good people that you did something careless and stupid that resulted in a death or an injury, than to convince them that a nice person like them suddenly turned into a murdering monster. A so-called “hair trigger” feeds right into their false allegation of an indefensible, unintended shooting.

Roughly speaking, 4 pounds is the factory-spec pull-weight basement for single-action semi-auto pistols and 5.5 pounds for striker-fired pistols.

Why would a plaintiff’s lawyer use the same false argument in a lawsuit? Different reason. In a civil suit, they’re looking for deep pockets. They know that if they win a seven-figure judgment against most people, the money just isn’t there to collect. But they know that most of us have at least a million dollars in homeowner liability insurance and automobile liability insurance. If you shot a home invader or a burglar who came at you when you caught him in the act, the homeowner’s insurance company has the money! If you shot the carjacker or road-rage attacker in self-defense on the highway, the auto-liability insurance company has the money! But if they allege that you did it deliberately, they’ve sewn the deep pockets shut, because most if not all such policies expressly exempt the insurance companies for having to pay for what is called a willful tort, that is, your intentional act that harmed another. (See Terry Graham v. Texas Farm Bureau for an example.) Self-defense by definition is an intentional act: a false allegation of “hair trigger” gives them the element of negligence, which is what liability insurance exists for. Thus, the motive, and once again, the “hair trigger” feeds into that allegation.

Learn From The Master–Massad Ayoob:

When in doubt about “factory spec,” call the manufacturer of the gun and ask their customer service department. As to “common custom and practice,” with striker-fired guns the standard seems to be the one long established by Glock: 5.5 pounds minimum pull weight. For single-action autos or traditional double actions in single action mode, figure roughly 4 pounds as red-line minimum. With revolvers, I would strongly recommend double action only. If you have a conventional DA revolver capable of being thumb-cocked to single action, I would recommend having it modified by a gunsmith or armorer to double action only. This means removing the single-action cocking notch internally, not just grinding down the hammer spur.

Author has done multiple “cocked revolver/hair trigger” cases, in some of which the allegation was false. He recommends defensive revolvers be rendered double action only.

The reason is, back when the double-action revolver was standard in law enforcement, it became almost a cottage industry among unscrupulous lawyers to falsely claim the gun had been “negligently cocked, creating a hair trigger effect.” There were, of course, cases where that actually did happen (see New York v. Frank Magliato), but there were also cases where it was falsely alleged (see Florida v. Luis Alvarez). This is why back in the service-revolver days, so many police departments (such as LAPD, NYPD, Miami, Montreal) modified their service revolvers to double action only. We would be foolish to ignore the decades of institutional history, and tragedy on both sides of the gun, that led to those policy decisions.

Note that I’m not saying never modify your gun or even its trigger in any way. Want to have a professional smooth up your trigger pull? Be my guest. I do. I’ve been an expert witness for the courts in weapons and homicide cases since 1979. I’ve done a number of “hair trigger cases.” Never once was the allegation that the trigger pull was too smooth. Every single time, the allegation was that the trigger pull was too light.

Editor's Note: This excerpt is from Massad Ayoob's Gun Digest Book of Combat Handgunnery, 7th Edition, now at

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