New guns and walking pins....

[LiveFreeorDie]

Sharing this story to see if others have had this problem, and if so, what brand had the problem and how did you fix it? I have a practically brand new (~500 rounds through it) S&W M&P 15 5.56 16" AR. Trigger began to fail to reset about every dozen or so times dry firing. Never had it happen during actual fire, but this is not a failure I would want when the weapon needs to function. Long story short, installed KNS anti-walking pin set for the hammer and trigger pins. Expensive, but solved the problem and improved trigger break. Seems S&W might be cutting corners by over-sizing the holes so the pins are easy to insert during manufacture. Trigger springs were binding on the original notched pins. This is a recipe for disaster. Anyway, just sharing to be sharing.

 

[Schultz]

I use KNS anti-walking pins in all my AR's.

 

[Parhams0508]

I have PSA's parts kit for my AR lower. I hope that when I finally get around to finishing it, this won't happen....

 

[Red Hat]

Reverse the direction of the pin. I've had that happen to me before. The trigger and hammer pins have a grove on one end of the pin. In the case of the trigger the hammer spring acts as a lock on the trigger pin. Sometimes one side or the other the notches in the trigger is not deep enough for the hammer spring to engage the trigger pin grove. You should feel a positive lock when you push the pin in if not always reverse the pin.

 

[LiveFreeorDie]

Thanks Red Hat, I didn't know that and those are interesting facts. But, after bragging about the expensive KNS pin set, the trigger still fails to reset occassionally while dry firing. Son also reported he had an M4 in the Army that would fail to reset, reported it, and it was fixed, though he doesn't know how. So, moving on from walking pins to triggers---do you guys think it's possible S&W makes crappy triggers, that I just happened upon a less than perfect one, or that I should just quit fretting about it and buy a nice (expensive aftermarket) trigger group? Therein lies another question--which trigger group to buy, and why?

Any and all help here will be greatly appreciated. There are some mighty smart folks in these here parts!

 

[fordnut]

Just had a problem that I feel is worth telling everyone about. Got a PSA rifle that had very few rounds thru it whenI got it.

When I took it to the range, had problems with it. It would fire 3 or 4 rounds then light strike the next one...then, it might fire a couple more times then light strike again.

I cleaned the rifle real good and took it and another PSA M4 that I have to the range. My M4 would fire the light strike rounds from first trip. I changed bolt carrier groups on the two rifles. It made no difference. Still got 3 or 4 rounds and then light strikes from the rifle...And, the M4 would shoot fine, as always...

I contacted the guy I got the rifle from, and he called PSA...They told him that they had had a problem with a few of their AR's like that. Someone had put the hammer spring in upside down...They said to switch the hammer spring around and it would be fine...

I called Clicker (Member Here and AR Geru) and also a neighbor. I took the rifle over to his house and he turned the spring over...

Went to the range today and the rifle ran 90 rounds without any problems...

Look into the top of the lower. The legs of the spring should come from the bottom of the coil and up to the pin....The spring in my rifle had the legs of the spring comming from the top of the spring...

Sorry so long winded, but, something to look out for, so I thought it was worth the typing...

Steve

 

[jjwestbrook]

i had the same thing happen on my first build . it would fire 4 rds and light strike the 5th . i compared it to my colt and the spring was in wrong. its an easy fix