What are AR15 Anti Rotation Pins?

Posted by Modulus Arms on 16th Dec 2022

What are AR15 Anti Rotation Pins?

Anti roll pins are one of the many features developed within the AR15 aftermarket over the 2010s. Today we cover their primary uses and merits in an AR build today.

What is an Anti Rotation Pin?

Anti rotation pins, also frequently called anti-walk pins, are AR15 trigger and hammer pins that secure tighter than conventional pins and roll pins. As implied by the name, AR15 anti rotation pins have mechanisms that prevent the pins from rotating while seated inside the lower receiver. The primary purpose of all AR anti rotation pins however is to ensure that the hammer and trigger pins do not wiggle and walk out of your AR over time. If the pins fall out it will take your fire control group with it, putting you out of the fight.

What Causes Trigger Pins to Walk?

Trigger pins can wiggle out of holes that weren’t made to spec. While this is not a problem for the CNC machines of big name AR brands today, it can be noticeable for people who aren’t perfectionists when drilling our 80 percent lowers by hand. If the holes aren’t big enough because you used a drill bit too small, then you obviously won’t be able to hammer the pins in. If the holes are too big… then your pins can have enough space to loosen itself out of its seated position. This can be more noticeable on 80 percent receivers that were drilled unevenly which is not uncommon.

Pros and Cons of Anti Rotation Pins

Mil spec AR15 trigger and hammer pins were developed to freely rotate with the trigger while spring tension kept the pins from walking out. Some users contend that allowing the pins to rotate is critical to ensuring smooth fire control group operation. The narrative behind this is that, with an anti-rotation kit installed, the hammer will have to resist the pins every time the hammer falls thereby increasing the potential for light hammer strikes. Although there isn’t reliable documentation of this fault, sufficient lubrication in the trigger pack should prevent this from becoming a problem at all.

For cleaning and lubricating purposes, we have in stock the trusty Hoppe’s 9 Lubricating Oil. Read more on how to properly maintain your AR in this previously covered topic.

If the primary purpose of installing anti rotation trigger pins is to prevent the pins from walking out, the long term solution is to ensure your mil spec lower has good tolerance or at the very least good warranty. It takes a LOT of shooting and abuse before your lower receiver begins to go out of spec. M4A1s that see plenty of full auto abuse for years function just fine without anti walk pins. If you begin to experience trigger and hammer pins walking out on a lower with proper tolerance, it is much more likely that the problem begins with the trigger spring.

But what if you used a lower with a softer material like in a polymer lower receiver? What if you drilled both holes from one side on a table with a wobbly leg when building out your lower? Well then like users who decided to use a non-spring tensioned trigger, you might be in the market for some anti roll pins.


  • Some people appreciate the aesthetic
  • Insurance
  • Secures cassette and drop in AR trigger packs that need it
  • Can be a cost-effective stop gap for out of spec lowers


  • Considered a band-aid solution for when it’s actually needed
  • Adds a failure point in operation

Best AR-15 Anti Rotation Trigger Pins

So you’ve decided to find yourself the best anti walk trigger pin you can find. Let’s help you get started on that journey by pointing you to some popular choices.

1. CMC Anti Walk Trigger Pins

Available in our own online store, we have the CMC Anti Walk Trigger Pins that come with each CMC drop-in trigger like the 3.5 lbs Curved Trigger. They offer a subtle look and are no more than just trigger and hammer pins each threaded internally to accept screws on both sides. Be careful to not over-torque the screws.

CMC also offers their same kit for older Colt lowers and the M&P 15-22 lower.

2. KNS Precision Gen 2

KNS Precision offers the Gen 2 Build-A-Kit with a set of nitrided backplates that ensure the screws aren’t budging from regular use once they’re installed. While the back plates most certainly offer extra insurance, the design makes it problematic for users that want to file down their pins to size for their lowers.

3. KNS Precision Gen 2 Mod 2

KNS brings another iteration of their Gen 2 anti-walk pins. The KNS Precision Gen 2 Mod 2 bears a set of back plates that come in the shape of a baby rattle for those that want a different flavor.

4. Wilson Combat Anti-Walk Hammer

Known for quality and robustness, Wilson Combat has their own set of anti-walk pins available in stainless steel and black finish. It’s compatible with all AR15s and AR10s that have 0.154” sized pin holes. The Wilson Combat Anti-Walk Pins start from $10.95 on their store.

5. Strike Industries SI Antiwalk/Antirotation Trigger/Hammer Pins

Strike Industries is a staple name for handguards and furniture in questionable tastes of cerakote. Nonetheless, their tolerance and quality is not called into question. Their take on anti-walk pins, the SI Antiwalk Pins, comes as a tool-less installation without any screws. This is a convenient feature during the removal process of the fire control group for maintenance. It comes with a tough nitrided finish and a backplate to eliminate walking.

Could you tell, we LOVE anti walk pins!

Anti-walk pins are one of the many niches of the AR market, while not critical to function, can be a good feature to have for peace of mind. If you’ve made a mistake building out your 80 lower, this can be a good stop-gap to have until we can get you another one to try again. Have you already gotten a stripper lower or milled out your 80 lower? Check out our lower parts kit and AR15 buffer kit today.