Has anyone ever had a problem with their trigger group pins walking on an M&P15. And does anyone know what size they are. I ordered the spring kit and was just wondering about the anti-walk pins?

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Grover Oathkeeper

Grover,
I though that these were mainly used when installing a self-contained trigger group, like a Timney, where the stock pins aren't held captive by the spring legs.

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- Bill

Never had a problem even with my select fire rifles which are what the pins are intended for.
Diameter is .154.

ETA:
Actually, Timney Triggers have vertical set screws that you tighten down on the pins once the trigger group is installed, those things ain't goin' nowhere!

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Hold my beer and watch this!

I just wondered, I ordered a spring kit today, just to check it out, if I like it I will keep it installed if not I will change it back....Little experimentation for $10. LOL

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Grover Oathkeeper

The non rotation pins from KNS will keep the pin holes in your receiver from wearing over time. They are also stronger than stock pins, and cannot walk out. I put them in every AR I build.

That's one argument I've seen, it was always countered with no one ever seeing receiver pin holes wearing out. The other argument I've read is since they don't rotate, it causes friction. I'd use them if I wanted but wouldn't have anyway of knowing if one is better than the other.

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Rod
M&P 22A, 40c, 15A, 15-22

My brand new AR had multiple issues with the pins walking. Took it out to a local range and between the 104 degree temp and the few hundred rounds I put through it, the hammer pin kept walking on me after every shot. I just ordered the anti-walk pins and replaced the stock ones to correct the problem. The pins I got are flanged and have a 1.5 mm allen slot to tighten in place. I was having all kinds of issues till I realized the silly pins had walked out causing the weapon to discharge even while on safe, each trigger pull required an additional pull to allow the trigger to flip back to ready position, etc. After replacing the pins...problems all solved. Wish you luck in fixing your issue.

+1. Love both models. Highly recommended.

I would venture to guess there is no reason a .22 type AR would need anti-walk pins. Just no real stress there compared to shooting 5.56 or 9mm. What I have seen and understand the reason behind the development of the KNS pins was that shooting 9mm uppers on select fire lowers could egg out the pin holes. This is due to the stress created by the 9mm bolt carrier and also why many builders started ramping those carriers. Lots of caliber uppers now available for a AR lower and I would think KNS pins would be a good low cost option for a center fire lower.