AR trigger pins walking

84ta406

NES Member
Rating - 100%
36   0   0
Joined
Nov 8, 2014
Messages
2,240
Likes
1,680
Location
Leicester MA
Noticed the trigger pins on my new-ish build were walking slightly while at the range last weekend, figured Id look at it today and sure as heck they work themselves right and left fairly easily. I double checked everything, hammer spring is installed properly etc. Just wanted to see what the general consensus here was about this? The lower is a Anderson and the LPK came from AWS when they did a GB last fall, no branding, just a clear baggie. I saw anti walk pins and such but I didnt know what works, and what doesnt. I dont need to spend a fortune, just dont want a failure.
 

mikelawtown

NES Member
Rating - 100%
79   0   0
Joined
Jan 20, 2013
Messages
6,956
Likes
2,109
Location
Mass Blah Blah Blah
KNS Anti's are going to do the trick but do you "Need" ? Nope, Use the .155 pins instead of .154 that have a deep groove,and that should do the trick.
 
Last edited:

mac1911

NES Member
Rating - 100%
68   0   0
Joined
Dec 26, 2008
Messages
29,115
Likes
6,585
I like to know why my pins are walking....had 2 lower kits that did.
1. The first thing I noticed with both problems is the pins had very shallow recesses. Both where what I believe to be CMMG lower kits...I bought some new pins.
That solved one trigger problem.
The other was a little hard to find and it took some time to actually see it.
There's a little tit on the end of the trigger arm near the pin hole that tit would actually contact the hammer spring and wedge it out of the pin recess.

I also gave a quick polish to the pin area that the hammer and spring rotate on. I basically just chucked them in the drill and gave a quick polish with turtle wax chrome polish on a 30 cal cleaning patch.
I used a little of the polishing compound on the pin and just pushed and twisted it around in the trigger and hammer pin holes... I have yet to have a,problem with those lowers.

Not the most technical fix but a DIY fix on some inexpensive parts is good for me.
 

84ta406

NES Member
Rating - 100%
36   0   0
Joined
Nov 8, 2014
Messages
2,240
Likes
1,680
Location
Leicester MA
I like to know why my pins are walking....had 2 lower kits that did.
1. The first thing I noticed with both problems is the pins had very shallow recesses. Both where what I believe to be CMMG lower kits...I bought some new pins.
That solved one trigger problem.
The other was a little hard to find and it took some time to actually see it.
There's a little tit on the end of the trigger arm near the pin hole that tit would actually contact the hammer spring and wedge it out of the pin recess.

I also gave a quick polish to the pin area that the hammer and spring rotate on. I basically just chucked them in the drill and gave a quick polish with turtle wax chrome polish on a 30 cal cleaning patch.
I used a little of the polishing compound on the pin and just pushed and twisted it around in the trigger and hammer pin holes... I have yet to have a,problem with those lowers.

Not the most technical fix but a DIY fix on some inexpensive parts is good for me.
This is exactly what it looks like is happening. I dont even see the hammer spring move when the pins slide.

Thanks Mike! Ill have to grab a set.
 

W.E.C

NES Member
Rating - 100%
1   0   0
Joined
Jul 29, 2012
Messages
8,289
Likes
4,468
Location
Boston
Chuck the trigger pin up in a drill, and using a jewelers round file, slightly deepen and widen the side groove for the hammer spring leg via spin filling. If needed, a touch of cold bluing will take the groove right back to black, give the surface something to hold the lube to prevent rusting
Make sure your hammer has the j pin spring in it. I had kits with the hammer and no j pin.
check your hammer spring .
 

W.E.C

NES Member
Rating - 100%
1   0   0
Joined
Jul 29, 2012
Messages
8,289
Likes
4,468
Location
Boston
You get what you pay for, unbranded aftermarket junk is junk,
buy junk pay twice.
learn lesson or spend more .there is a ton of knock off crap out there,

brand name parts don't need keeper screws.
 

chris_1001

NES Member
Rating - 100%
25   0   0
Joined
Dec 3, 2008
Messages
3,308
Likes
673
Location
MA
On standard triggers, yes. Some custom ones are designed only for use with anti-walk pins.
Yes, I was referring to standard mil-spec. Sounded like that's what was being used by the description.

My Timmney uses set screws to "wedge" the standard pins in place and my CMC uses anti walk pins. On a side note, while my Timmney is a great trigger, I'm not much of a fan of the way they lock the pins.
 

84ta406

NES Member
Rating - 100%
36   0   0
Joined
Nov 8, 2014
Messages
2,240
Likes
1,680
Location
Leicester MA
Well I pulled it all apart just now. The pins that were in there look real crappy. I had another set from a "spare parts" kit I bought and swapped them in, they actually had a semi circular groove and looked deeper. Anyways heres the ones that were in there, look pretty beat up after only 160rds.

- - - Updated - - -

I am using a standard trigger, feels pretty smooth and light but nothing special.
 

Attachments

mac1911

NES Member
Rating - 100%
68   0   0
Joined
Dec 26, 2008
Messages
29,115
Likes
6,585
Well I pulled it all apart just now. The pins that were in there look real crappy. I had another set from a "spare parts" kit I bought and swapped them in, they actually had a semi circular groove and looked deeper. Anyways heres the ones that were in there, look pretty beat up after only 160rds.

- - - Updated - - -

I am using a standard trigger, feels pretty smooth and light but nothing special.
Yes there are some cheap stuff out there. I didn't like the feel of the finish on a LPK I received so I tossed it in the brass tumbler for a few hours. That was one of the discount kits that came in the "rainbow" bags. Each part group came in a smaller colored bag. I bought it for a cheapo build.
 

84ta406

NES Member
Rating - 100%
36   0   0
Joined
Nov 8, 2014
Messages
2,240
Likes
1,680
Location
Leicester MA
The grooves in the pins are so shallow and narrow for that matter that the hammer spring legs werent even sitting in the grooves. Think it was just cheap pins.

Thanks Stryker, ordering a set after I post this.
 

84ta406

NES Member
Rating - 100%
36   0   0
Joined
Nov 8, 2014
Messages
2,240
Likes
1,680
Location
Leicester MA
Picked up the KNS pins from Primary Arms, havent shot the gun yet but I dont see how they will move. I did buy the .155 pins and they fit great except for my hammer, I had to hone it out a little for the pin to fit through. Will post another follow up next friday when I finally head to the range.
 

Attachments

Rating - 100%
29   0   0
Joined
Feb 20, 2013
Messages
13,727
Likes
2,144
Ovalled pins is fairly common on 9mm AR's due to the heavier bolt slamming the hammer back pretty hard in the straight blowback. KNS pins are the most common solution for this.
 
Top Bottom