View Full Version : Help Me with loose AR10 Trigger & Hammer Pins

10-01-2009, 2:42 PM
Hey Guys,

I'm working on my AR10 build (Aero) and I'm having trouble with my trigger pin and hammer pin.

I have a Timney AR-10 Drop-In Trigger, and a few AR10 LPK's from Armalite. (I actually bought 3 LPK's from Armalite, and tried all three sets of trigger/hammer pins, and I'm having problems with all 3 sets.)

The pins basically just slide out - if I turn the lower sideways, these two pins will just fall out.

Is there something wrong with my lower, or the pins, or am I doing something incorrectly with my Timney Trigger? I googled it and found a post on AR15.com that said "the receiver doesn't hold the pins in position - the J-pin (inside the hammer) and the tail of hammer spring is supposed to do that.

The J pin in the hammer should engage the center groove in the hammer pin and the tail of the hammer spring should rest on top of and engage the groove on the end of trigger pin."

How do I verify this? Does a Timney trigger even have a J-pin? What's a J-pin anyway? :confused: :confused:

So I was looking at getting some new ones, i.e. the KNS Precision Gen 2 Mod 2 Non-Rotating Hammer and Trigger Pins (http://www.pkfirearms.com/content/1/20/4/18).

But I don't know which ones to buy for my AR10.

They have .154, .1555, and .170 diameter. What's good for my AR10?

Help please? Any advice is welcomed. Thanks!


10-01-2009, 4:24 PM
Did you read the Timney directions?

The Timney trigger has set screws inside on the sides of the housing.
You drop in the trigger assembly, slide in the pins.
When you crank down on the set srews it they bite into the bottom of the lower and press up against the pins, holding them in place.
Then you install the keeper set screws on top of the primaries to keep them from backing out.

The J spring is on a standard hammer.



10-01-2009, 4:52 PM
Thank you.

I bought my Timney used, from a friend who parted out his AR-10 - I did not have the instructions.

I will go try this right now.

Thanks again! :thumbsup:

10-01-2009, 7:36 PM
You may want to consider the below anti-walk pins if you are worried about the allen screws backing out and your pins falling out. I used the JP pins on my Timney.



10-01-2009, 7:49 PM
I have Timney triggers on all my AR rifles and you have to make sure that you have the set screws all the way down.

To do this you must back out the first pair of screws completely and then set the other screws down so that they press against the receiver pushing the trigger group up all while keeping the trigger pin and hammer pin in place and while working around the hammer spring.

Once you have the bottom pair of set screws firmly pushing the trigger group up and the pins are firmly in place the 2nd pair of set screws are put back in place snuggly against the first pair of set screws. A little drop of blue loctite works on the first set just as long as is remains on the threads and doesn't wind up in the allen wrench holes on the screws.

I went with the KNS 2nd generation anti walk pins on all my ARs and they make it a bit easier to install the trigger group.

10-01-2009, 9:13 PM
It worked! I see what I was doin wrong. It's snugly in there now.

Thanks guys - Calguns is awesome. :thumbsup: