Strike Industries Anti-walk and Anti-rotation AR-15 Trigger/Hammer Pins

Strike Industries’ solution to the problem of rotating and walking out AR-15 pins is pretty unique and simple as in the case of many other of their products. The pins of their anti-walk/anti-rotation system extend a bit over the lower receiver exposing a groove. The retention itself is accomplished by an external clip.

Judging by the appearance of the clip, it probably can spring open a little bit to snap on the installed pins. The anti-walk mechanism is obvious – the clip rests in the exposed pin grooves and restricts their horizontal movement. The anti-rotational function is accomplished by the geometry of those additional grooves. If you look closely at the above image you will notice that these grooves are not cut around the circumference of the pins. They are rather parallel side cuts. The result is a couple of flat surfaces, which house the clip and prevent the rotation of the pins around their axis.

Another advantage of this pin system that SI points out, is the tool-less installation and absence of screws seen in competitors’ products. However, the slots in the pin heads and the cutout in the clip are probably there to allow using a tool (e.g. screw driver) to align the pins and remove the clip respectively.

The SI pins are made of S45C steel with QPQ (Quench Polish Quench) Nitride finish. The surfaces of the pins are also polished to reduce the friction between the pins and the hammer or trigger. The pins’ diameter is .154″.


The Strike Industries anti-walk/anti-rotation pin set is now available through their website at $14.95.





Hrachya H

Being a lifelong firearms enthusiast, Hrachya always enjoys studying design, technology and history of guns and ammunition. His knowledge of Russian allows him to translate and make Russian/Soviet/Combloc small arms related information available for the English speaking audience.
Should you need to contact him, feel free to shoot him a message at Hrachya@staff.thefirearmblog.com


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  • Palmier

    I never knew this was a problem.

    • PK

      It only becomes a problem when you have an (untensioned) FCG such as a drop in with no means of retention.

  • Thomas Bennett

    Does anyone have anything more than anecdotal evidence that pins rotating causes any issue, or that pins will walk out of the receiver and bind the trigger mechanism?

    HONEST question, not sarcasm

    • Tyler McCommon

      I’ve known some aftermarket match triggers to have issues if the pins rotate. (Hyperfire trigger I own began dumping mags. They recommended anti rotation pins which I installed and it seemed to fix the issue.) But milspec and drop in box triggers I’ve never seen have an issue nor had one occur myself.

      • Dougscamo

        Thanks for that info because I was like Thomas Bennett and Palmier on this…

        • Thomas Keshel

          While working at a gun store that builds and works on ar15s I’ve only ever seen one rifle that had a problem with standard pins walking out. We were pretty sure the holes were out of spec but the guy didn’t want to get a new lower so it was a cost effective remedy to the problem. Other then that one case though they’re a nice to have item not a need to have.

      • gene

        I’m not sure I can mentally see how rotation of cylindrical pins can cause that. Especially since several 3rd party triggers come in drop in packs which puts a cylindrical pin in a tube. Not tryping to be snarky or anything, just having a hard time seeing what physically happens which causes it.

        • Tyler McCommon

          You clearly did not read my entire comment. I said I have never seen or had issue with a drop in box trigger.

          • gene

            You clearly did not read my entire comment. I asked about the _mechanics_ of how rotation causes issues trying to understand what you experienced.

        • Marcus D.

          The original grooves in a mil-spec pin is designed for the legs of the springs to slip into, effectively holding the pins in place. Drop in triggers eliminate this feature, since the spring legs are inside the box. There are two solutions, should your pins start to slid out of the receiver: anti-walk pins or a trigger group that has set screws that freeze the pins against the top of the hole in the receiver.

          • gene

            That makes sense – danke.

    • PK

      Yes, but only with full-auto and/or rapid silenced fire. I’ve had pins dance right out of the receiver.

      Usually these pins are meant to hold in a box-style FCG, these days. The original purpose never made a lot of sense in the civilian world. For this particular problem, I’ve experienced it repeatedly… pins without the retention groove being engaged by anything can and do tilt right out of a receiver.

    • Outside of machine guns, and blowback guns I haven’t heard of a reliable case of someone damaging their receivers with normal pins.

    • Bill Jordan

      Ive had 2 or 3 receivers that would walk trigger pins and disable the trigger. That is with proper 3 notch pins, and the hammer pin contacting both of the grooves like they should.
      Should mention it was with lighter weight springs, but shouldn’t matter all that much.
      Now I just buy a 20 pack of threaded pins and screws from a guy on ebay for under $15.

  • int19h

    So, a lot like AK, except inconveniently placed outside of the receiver.

  • PK

    I’ve made similar pins, in a pinch. Sometimes I have an extra box FCG and no KNS pins, and these do the job. I saw an ad from SI recently via e-mail and ordered one just to see…

  • FWIW

    I got a simple pair of anti-walk pins on ebay because the ones on my 9mm AR kept walking pretty far after a few hundred rounds. Never enough to cause a malfunction before I’d notice while cleaning and tap them back to center, but it was a $10 fix so I figured why not. This seems like a good solution and I’ve liked SI’s other products. I assume that was an issue caused by the relative violence of the blowback action on the 9mm carbine–never had any pins walk on my 5.56 ARs, ever. But then again I don’t use drop-in triggers.

    • John Burridge

      I’ve had a similar experience with my JP Rifles 9mm carbine- it started doubling at the range. One of the pins had worked itself out about 1/3 of an inch. I replaced them with KNS anti-walk pins and no more accidental felony. And who cares if the pins rotate as long as they stay in…

  • Leroy Jenkins

    KNS ones are much better looking.

    • MrBrassporkchop

      I have a few kns pins I actually like these they’re more utilitarian.

  • Only the civilian market can come up with problems where over 60 years of military service can not.

    • Michael Gallagher

      Most, if not all, military rifles don’t have aftermarket triggers which may need this. (guessing that some military shooting team somewhere may have one in a rifle) The need came about with the introduction of early drop in target triggers for sport shooters. My first drop in trigger came with a set, since then I have upgraded to the KNS pins and don’t have an issue.

  • Spencerhut

    Those pins are designed to rotate. Another solution to a non existent problem.
    P.S. Looks like a take down catch off a Tokarev TT33.

    • Jaune Arc

      The clip fits into flats on both pins, which would prevent rotation.

  • steveday72

    I really don’t like the “flat blade screwdriver” head as seen on one side. It makes it look like something knocked-up by a junkyard.

    Normally SI makes some interesting parts, but these are worse than the KNS.