Do I need anti-walk pins?

[dabluesguy]

A few days ago I installed a Timney trigger in my M&P 15 and went out a shot a few hundred rounds. I'm elated with the crisp 3-lb. trigger. Our day ended with a failure to fire and when checking for the problem I found that the hammer/trigger pin had fallen out and the other one was coming out. This was after about 200 rounds or so. Did I install the pins wrong or do I need to get some anti-walk pins or something equivalent? Thanks in advance.

 

[gyvel]

My suggestion is to get some type of anti-walk pins before you wallow out the holes in your receiver.

 

[tulsamal]

I personally like the KNS pins. What are they, $25 from Brownell's? Whenever I put a new trigger in an AR, I put those pins in at the same time. I saw the stock pins drift on M16's in the Army too many times. Makes the rifle just stop and leads to confusion. Easy enough to fix once you figure what is wrong but will you be able to do that if people are shooting at you? Figure it out and fix it and return fire in five seconds? Not me!

Gregg

 

[gyvel]

If I'm not mistaken, "walking pins" can cause malfunctions like full auto fire as well.

 

[dabluesguy]

Full auto? Hmmmm...no I guess I don't want that at this time. You guys convinced me to get the anti-walks. I'll order them tomorrow. Thanks for your replies.

 

[sailskidrive]

It sounds like the pin holes on your receiver are a little rounded out or over sized or your pins are a tad small. The Timney trigger is completely self contained and doesn't really put an pressure on the pins, which is my guess as to why yours fell out.

I would go with a set of KNS pins or at a minimum a set of oversized pins.

 

[Achilles11B]

I had the pins start to walk out of an M4 I was issued in the Army during rifle qual. Qualified faster, but surprise-auto isn't quite as accurate as semi.

The full-auto-without-warning thing is what I would be worried about. No need to have a negative encounter with Officer or Special Agent Friendly when it can easily be avoided. Good call on ordering the anti-walk pins and good looking out for ID'ing the problem before it started.

 

[zippy13]

If I'm not mistaken, "walking pins" can cause malfunctions like full auto fire as well.

For sure!
My buddy's bottom-dollar AR started doubling resulting from the pins walking. The first time it was the trigger pin and later the hammer pin. Luckily there wasn't a overly zealous ATF agent at the range.

 

[madcratebuilder]

Did you install the pins in the correct location? Hammer pin and trigger pin are different. Hammer pin has a retaining groove in the center (except ArmaLite D spring) and the trigger pin has two grooves, one near each end. Installed correctly you should not have any pin walk.

I do use the KNS non-rotational pins in most my AR's. They improve trigger feel and eliminate any receiver wear in the pin holes.

 

[geetarman]

When I bought my first AR platform, the Timney trigger was installed by the armorer.

The screws in the trigger that are supposed to apply pressure to the pins backed out and I had a pin walk out at the range.

I have put the KNS anti-walk pins as a precaution on all my AR platforms and have yet to have one of them come loose.

Geetarman

 

[KLRANGL]

Agreed with geetarman, I recommend anti-walk pins to all my friends who plan on having high round count ARs. I have seen some high round count lowers have their pin holes enlarged by the pins rotation (most people will never get that high though). Stop the rotation, and the holes wont enlarge. The positive capture also prevents the pins from physically coming out for any reason.

 

[madcratebuilder]

Why does everyone call the KNS pins "anti walk"?.

They are "anti rotation pins".

Anti walk pins normally rotate and are secured by a e clip or cap screw on each end.

"anti walk pins"

"anti rotation pins"

They are very different in form and function.