EXCLUSIVE: The Original DROP-IN AR-15 Trigger. First Ever Photos of T86 Rifle Trigger Published Online

Two days ago I published a blog post with diagrams of the REVOLUTIONARY Taiwanese T86 rifle. This AR-15-style rifle featured not only a self-contained piston gas system back in 1998, long before the piston-AR craze in the USA, but it also featured the first drop-in trigger for an AR-15. Sadly this rifle was as unknown in the West as it was innovative. 

In that blog post I asked readers, living in countries where the T86 is in service, if they could try and obtain photos of its trigger system. Being a relatively obscure rifle that has only ever seen military use, I did not have a lot of hope. Imagine my surprise to get an email from an incredibly well-placed source who took the time to strip a T86 and take high resolution photos for TFB. As far as I know no detailed photos of the trigger system have ever been published online. I was not even able to find low-resolution photos, only diagrams.

The source has sworn me to secrecy, and so I will not even hint as to who or where the source is.

The design process of the T86 began in 1992 and ended 6 years later in 1998. The rifle went into production in 2000 and unfortunately did not see wide adoption due to military budget cuts, but it was exported to Jordan and the UAE.

The external dimensions of the T86 lower receiver are the same or very close to a standard AR-15 lower, but what is really interesting is that there are no trigger pins or hammer pin holes.

t86 rifle lower ar15

t86 rifle lower

No pins means no pins to lose in the field and the lack of holes also gives it an aesthetically pleasing look (in my mind at least).

t86 rifle trigger


The trigger itself is self contained. It requires no pins other than the selector switch. It literally drops-in. The T86 trigger is larger than the AR-15 drop-in triggers on the market today. Compare it to the Rise Armament drop-in trigger below which does not enclose the selector switch. Rise Armament Trigger

Other than being physically larger it appears to operate the same as a regular AR-15 drop-in trigger. Both have pins in the same position to hold the trigger components. Unlike commercial drop-in triggers which fit into mil-spec lower receivers, the internal dimensions of the T86 lower were modified to hold its trigger in place without the need for receiver pins.

t86 trigger insert

t86 trigger inside

As you can see the tolerances are tight and there is no play between the trigger and the lower receiver. This is quite a beautiful system!

Unfortunately I do not have photos of the piston system. The only diagram I have shows a very interesting self-contained unit that contains both the piston and gas tube. This may have been the first AR-15 piston system to be adopted by any military (Colt developed the first AR-15 gas piston, the Colt 703, but only two prototypes exist).


This rifle was ahead of its time, but sadly because of defense budget cuts in Taiwan in the late 1990s, it never saw the widespread use it may have. Earlier today a gun industry veteran emailed me saying he thought we will soon see lower receivers designed to accommodate drop-in triggers like the T86 system. This would get around Mossberg’s patent, which essentially patents the use of pins to secure a drop-in trigger, not the trigger itself.

Read more about the patent situation below:

[Breaking] Mossberg Suing Manufacturers of Drop-In Triggers

BREAKING: The Truth Behind Drop-in AR-15 Triggers. They Date Back to 1998.

Update: The very first Mossberg US Patent infringement suit in 2012 Vs. Timney

CMC Triggers Makes Statement

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • dan

    this is why the patent and IP laws need to be scraped and rebuilt from the ground up they are stupid and out dated if the use of 2 pins in a certain way is the difference of legality

    • Glenn Bellamy

      This shows that the patent laws are working just fine. If you want to make the old style trigger pack that does not use pins through the receiver walls, you are free to do so.

      • John

        Really? They patented putting a pin through another pin which has the same function as the original pin. They patented a design constraint. It’s like patenting that your aftermarket rims have the correct number of lug bolt holes for the car they’re for.

  • Twilight sparkle

    We could just do this the old fashion way and snub mossberg till they grow a brain. This legal nonsense has made me decide on looking towards Kalashnikov based shotguns instead of a 930.

    • Amaterasu_Junia

      SAIGA. No more needs to be said.

    • uisconfruzed

      Benelli & Winchester

  • Austin

    First, Eugene Stoner also designed a piston AR, the AR180.

    Second, As for the impact this will have on the current cases, I don’t know if it will impact them at all due to the patent in question being based on using existing pins in the lower assembly of the gun to secure the group in place.

    Lastly, could the group on the T86 be considered a fire control group, like the P250 and P320 due to it also incorporating the fire selector?

    • borekfk

      Actually the AR-180 is based off of the AR-16 which was in 7.62x51mm. Stoner designed the AR-16, but left ArmaLite shortly afterwards. The design was scaled down for 5.56 and redesigned by Arthur Miller.

      • Austin

        The AR-16 was only in prototype and even so that would still be a piston AR variant just initially AR-10 based

    • The AR-180 was designed because of patents. Stoner couldn’t use the DI system as invented on the AR-10/AR-15 as those patents were sold to Colt. He used the piston arrangement because it wasn’t patented. And he used stamping to make it cheap to produce by relatively unskilled laborers.

    • Christian Hedegaard-Schou

      It IS a fire control group.

      So is the trigger in your regular AR15.

      What I think you’re getting at is can it be called a receiver? No. Because it drops into a (modified) AR15 lower, and that’s already been determined to be a receiver.

      • Austin

        Then how does sig get around that with their pistold? The trigger group is the serialised part.

        • Christian Hedegaard-Schou

          What do you mean? What is it that you’re having trouble understanding?

          Yes, the trigger group is the serialized part in the Sig pistol (actually, it’s not the trigger group but the lock frame, which contains the lockwork, aka the trigger group).

  • kzrkp

    wow i love that pin absent lower design. shame cant do it with the AR15 without making it impossible to use standard triggers.

    • PK

      Standard triggers would be easy enough to drop into the housing intended for better parts, wouldn’t they? The only real change would be using shorter pins to retain the trigger/hammer inside the drop-in box.

  • Nocternus

    Couldn’t the manufacturer’s in question just not drill the holes in the aluminum housing and instead include a couple drill bits and punch the hole locations. Call it an 80% trigger pack. Then it would be the user that is violating the patent not the manufacturer?

    • Yes

    • Glenn Bellamy

      No. When a manufacturer sells a “kit” and instructs the user how to use it to infringe a patent, that is known as inducing infringement and the manufacturer has indirect lianility

      • Nocternus

        Who said anything about instructions.

        • True it seems it would be so obvious there would be no real need for an instruction sheet.

        • Glenn Bellamy

          It can still be inducing infringement when the manufacturer knows it will be used in an infringing way and there’s no noninfringing use for it.

          • Nocternus

            Noninfringinguse is as a paper weight. Coffee table conversation piece. Etc.

            How long have they got away with selling brass knuckles as belt buckles or paper weights.

            80% drop in trigger paper weight for sale. Holes pretapped includes drill bit.

    • Nocternus

      I am also curious if someone improves on the original design does that new design still fall under the first patent or can the person that made the improvements file a new patent. Like in the case of the POF drop in triggers they added silicon tubes under the trigger pack that make it where you don’t have to fiddle with set screws. Does this improvement on the original design constitute a new design or just because it is a trigger pack for an AR15 that utilizes two screws its automatically under the first patent?

      • PK

        “I am also curious if someone improves on the original design does that
        new design still fall under the first patent or can the person that made
        the improvements file a new patent.”

        At that point, a subsequent patent can be filed, referencing the first as prior art and describing the improvements.

        I’d also like to point out Elftmann’s use of roller bearings as a distinct improvement over other drop-in FCGs.

      • Glenn Bellamy

        Improvements can be patented. In some cases, the improvement can’t be used or sold until the first patent expires or gives a license. On the other hand, the owner/inventor of the prior invention can’t use the improvement without a license from the improvement inventor.

    • Interesting idea for sure!

  • Julio

    TFB at its best.

  • PK

    Outstanding work. I love this type of journalism!

  • Ambassador Vader

    drop in trigger mfg will just no longer refer to them as pin holes, for now on they shall be known as lubrication holes, any lining up to the receiver pin holes is purely coincidental.

    • Glenn Bellamy

      If pins through the receiver walls aren’t used, great. No infringement.

      As stated about the prior art, above: “Unlike commercial drop-in triggers which fit into mil-spec lower
      receivers, the internal dimensions of the T86 lower were modified to
      hold its trigger in place without the need for receiver pins.” Thus, McCormick’s invention that allows the use of a drop-in trigger pack that does not have to be fitted exactly to the inside of the receiver and uses the two existing, precisely placed pin holes to support the unit in the proper place.

      • Ambassador Vader

        I know it was sarcastic. A marketing ploy. Everyone knows what solvent traps are used for *cough*. Everyone would know they are trigger pins, but mfgs would call them lubrication points to avoid law suits.

  • Jess Johnson

    Trigger packs are nothing new. They pattented a method of using hollow pins to hold the hammer/trigger and use standard AR pins to pass through those, requiring none of the custom machining of the lower the T86 required.

  • guest

    I fail to see any “revolutionary” aspects of any of it.

    • Camilo Emiliano Rosas Echeverr

      Because you’re looking at it from the future.

      • guest

        May be, or it may also be that I deal in the exact meaning of words instead of hype terminology.

  • PeterK

    Cool. Great coverage of an interesting story and topic.

  • Krummholzt

    So, that’s not anticipatory. There are no pins having openings to receive other pins, which is required by all the claims. That makes this an obviousness case, which is tougher.

    Sometimes, a patent is valid.

  • NebulousCat

    Stop buying Mossberg and CMC products. If they are not in business they can’t sue anyone.

  • Gunner4guy

    Instead of using larger diameter ‘hollow’ pins(or sleeves?) for the trigger and other items to ride on inside a small housing and smaller solid pins to go through them into the sidewalls of the receiver, why not junk the ‘sleeves’ and use solid pins for securing the FCG inside the weapon? I’d think that since the original Armalites and the later Colts, Harrington & Richardson’s, etc. used solid pins that alone would negate Mossberg’s patent trolling suit….or am I missing something?

  • Eric X Ericx

    There goes Mossberg’s lawsuit! Bwahahahhahaa!!! Live by greed, die by greed!


    The cassette type trigger housing has been around for years. If I recall correctly the German G-3 uses a cassette housing. Patent No. 4,679,487 (Houseman) is an excellent example of the cassette design, and was in effect when McCormick filled for his trigger in a beer can patent. For some reason McCormick failed to discover the Houseman patent, and did not disclose it in his application patent search.

    One requirement for a patent is that the design is not obvious. Using the existing trigger pins, to retain the cassette, is obviously obvious. Installing the cassette in the receiver is also obvious, and has been covered in previous patent applications including 4,679,487. I think Mr. McCormick has a vanity patent exhibiting no originality, and I hope that the effected manufacturers will, as a group, challenge the McCormick/Mossberg patent.