Trigger Pin....

[walter34payton2002]

Hey guys.....

I am running a complete BCM upper and Spikes lower with G&R LPK. Fired about 400-500 rounds today without a hitch except I noticed after every 30-40 rounds the trigger pin will work its way loose until it comes out. I'm not going to say what happens when one side of the pin is out, but its not good and that happened. The pin wont stay in with 30-40 rounds of recoil. Any ideas as to why and even if we come up with a solution I feel safer with anti movement pins. Doesn't KAC make some???

[5pins]

More then likely you have the hammer spring on incorrectly. The legs of the spring should be on top of the trigger pin.

[walter34payton2002]

It is on correctly.....

[C4IGrant]

As 5pins stated, look at this first. If that is not the case, then either the pin is undersized OR the pin hole in the receiver is out of spec (both can happen by the way). If you have a set of calipers, measure the pin and the hole.

If the hole in the receiver is .155, you might need to go with some KNS pins.



C4

[walter34payton2002]

Thanks for the response Grant. I went with this(http://www.brownells.com/.aspx/sid=52497/pid=26944/Product/AR_15__154__DIA__NON_ROTATING_PINS), but it is the .154. I bought this so it would come quickly before your response.....The .154 should do the trick right, even if the hole is our of spec to the tune of .155??? Thanks.

[Eric]

On a rare occasion the groove machined into the pin is undersized and fails to catch the spring leg. The resulting malfunction of a dislodged pin can indeed be interesting.

[walter34payton2002]

I took a closer look under the light and for whatever reason the hammer spring legs I guess just weren't engaging the slots in the trigger pin. I took it down and reinstalled and the legs set nice now. Weird......But no more movement. Thanks guys. I will see if I can cancel the knee-jerk reaction KNS order I made.

[Belmont31R]

Yes KNS pins are not needed. If you have walking pins, like in this case, its because either something is out of spec or was not put together properly.




Glad you got it sorted out.

[eightmillimeter]

Was there any gouging of the hole in your lower when the pin came out too far and "malfunctioned".

[walter34payton2002]

No, at least it seems fine. I took the fcg apart and reinstalled everything. I have built many a ar and everything was correct as far as I could tell. I don't have a caliper but I compared the pins to others and they were fine to the naked eye. The legs just didn't seem like they engaged the grooves, but they do now after I made certain they were seated. It was just strange all around.

[eightmillimeter]

What I was trying to say was that excessive and improper maint. causes wear.

[C4IGrant]

Thanks for the response Grant. I went with this(http://www.brownells.com/.aspx/sid=52497/pid=26944/Product/AR_15__154__DIA__NON_ROTATING_PINS), but it is the .154. I bought this so it would come quickly before your response.....The .154 should do the trick right, even if the hole is our of spec to the tune of .155??? Thanks.

Glad you got it sorted out.


C4

[Iraqgunz]

You can disassemble them everyday of the week for 20 years and nothing will happen. The caveat is that you have to do it in the correct order and with the correct tools.


Thats good. I tend to stay out of the fire control parts as much as possible. Those holes seem to loosen up when people start removing triggers and hammers every other day. Especially when using the oversized pins.

[KrampusArms]

Thought I might ask this here to avoid starting a new thread. I have a CMMG lower, and the hammer pin always walks out a bit. After a few rounds it starts to peak out the right side of the receiver. Its odd. Only say a half millimeter, and it never protrudes farther. I guess the J hook in the hammer is capturing it, but Is there any way to remedy this? Should I try reversing the pin?

[markm]

Try a different hammer. Something isn't right there.

[Iraqgunz]

Your "J" hook is most likely worn out or damaged. I would start by replacing the pin first. If that doesn't help replace the hammer.


Thought I might ask this here to avoid starting a new thread. I have a CMMG lower, and the hammer pin always walks out a bit. After a few rounds it starts to peak out the right side of the receiver. Its odd. Only say a millimeter or two, and it never protudes farther. I guess the J hook in the hammer is capturing it, but Is there any way to remedy this? Should I try reversing the pin?

[KrampusArms]

Ok thanks Iraq & MM. I'll try that