The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: Semi-automatics

Reply
 
Thread Tools Search this Thread
Old March 25, 2020, 11:54 AM   #1
ECM4
Member
 
Join Date: February 18, 2019
Location: West Virginia
Posts: 38
AR Hammer Pin is walking out.

Just bought a drop in trigger to put in my AR9. Once I got it all together I was testing the trigger. Dry fired a few times and my hammer pin was about to fall out. What causes this and what is the fix? I have a feeling the holes in the drop in trigger are loose and maybe the trigger is just bad. Anyone ever have this problem? How did you fix it?
ECM4 is offline  
Old March 25, 2020, 12:08 PM   #2
FrankenMauser
Senior Member
 
Join Date: August 25, 2008
Location: Potatoes and Hops
Posts: 12,185
It should have some type of pin retention.
Check the instructions and check your pins. Make sure they're installed in the correct orientation.
__________________
Don't even try it. It's even worse than the internet would lead you to believe.
FrankenMauser is offline  
Old March 25, 2020, 12:15 PM   #3
44 AMP
Staff
 
Join Date: March 11, 2006
Location: Upper US
Posts: 20,972
Incorrect information removed...
__________________
All else being equal (and it almost never is) bigger bullets tend to work better.
44 AMP is offline  
Old March 25, 2020, 12:30 PM   #4
Sharkbite
Senior Member
 
Join Date: November 4, 2013
Location: Western slope of Colorado
Posts: 3,324
IIRC, a self contained drop in trigger group does not allow the hammer spring to hold the pins in. If this is fact one of the “cartridge” type trigger groups. Like the POF units i use, some type of anti-walk pins should be used.
Sharkbite is offline  
Old March 25, 2020, 12:56 PM   #5
ECM4
Member
 
Join Date: February 18, 2019
Location: West Virginia
Posts: 38
Thanks for the info guys. This is the first drop in trigger I have ever used. I will check the retention pins on the bottom that push up against the lower receiver. Maybe I didn’t tighten them up enough. then I can order new hammer/trigger pins if that doesn’t work.
ECM4 is offline  
Old March 25, 2020, 01:17 PM   #6
stagpanther
Senior Member
 
Join Date: March 2, 2014
Posts: 6,858
Usually the hammer and trigger pins (assuming your drop in re-uses standard AR pins) will be notched with grooves on the ends. Make sure you put both pins in the same orientation, usually there's enough room to slip a thin c-ring to help.
__________________
If you’re ever hiking in the woods and you get lost, just look up and find the brightest star in the sky and you’ll know which way space is.
I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!
stagpanther is offline  
Old March 25, 2020, 02:02 PM   #7
imashooter
Senior Member
 
Join Date: December 28, 2013
Location: Alabama
Posts: 248
Quote:
Thanks for the info guys. This is the first drop in trigger I have ever used. I will check the retention pins on the bottom that push up against the lower receiver. Maybe I didn’t tighten them up enough. then I can order new hammer/trigger pins if that doesn’t work.
Normally those bottom screws should just kiss the bottom of the well. If addressing them doesn't work, redo them again where they just touch (or totally collapse them where they don't touch) and either way, install a set of anti-rotation pins such as KNS.
imashooter is offline  
Old March 25, 2020, 05:03 PM   #8
9x19
Senior Member
 
Join Date: October 15, 1998
Location: Sherman, TX USA
Posts: 3,557
In my guns, the hammer has a spring wire contained in the hammer (there is a groove milled into the center of the bottom radius and a hole extending up into the hammer) that bears against the center groove of the hammer pin when it is installed. That spring wire retains the hammer pin.

The hammer spring legs do rest atop the trigger pin to prevent it walking, but there is no way the forward legs of the trigger spring will go over the hammer pin.

All five of my cartridge type FCGs (three POF, two Rise Armament) came with anti-walk pins, as both pin holes are smooth with no built-in retention.
__________________
Make mine lean, mean, and 9x19!

Last edited by 9x19; March 26, 2020 at 10:12 PM.
9x19 is offline  
Old March 25, 2020, 06:16 PM   #9
ECM4
Member
 
Join Date: February 18, 2019
Location: West Virginia
Posts: 38
Quote:
Originally Posted by imashooter View Post
Normally those bottom screws should just kiss the bottom of the well. If addressing them doesn't work, redo them again where they just touch (or totally collapse them where they don't touch) and either way, install a set of anti-rotation pins such as KNS.
The pins at the bottom were the problem. Directions said to not over tighten so I barely got them to touch when originally installed. I went back and I torqued them down pretty tight it actually tightened up my hammer pin. I at-least feel comfortable shooting it now but I will just get some new pins to make sure.
ECM4 is offline  
Old March 25, 2020, 06:52 PM   #10
Screwball
Senior Member
 
Join Date: May 16, 2012
Location: ME
Posts: 635
KNS pins are sometimes viewed as a gimmick... but for the one lower that constantly had the pins walking, I actually toss them on all my lowers for piece of mind.
Screwball is offline  
Old March 25, 2020, 07:28 PM   #11
Kreyzhorse
Senior Member
 
Join Date: April 12, 2006
Location: NKY
Posts: 12,234
44 AMP is dead on.
__________________
"He who laughs last, laughs dead." Homer Simpson
Kreyzhorse is offline  
Old March 26, 2020, 02:34 AM   #12
DnPRK
Senior Member
 
Join Date: August 24, 2001
Location: LC, Ca
Posts: 1,887
ECM4, I assume you installed a Timney drop-in hammer/trigger group.

Personality, I wouldn't trust two tiny set screws to hold the hammer and trigger pins in place. KNS pins or similar are the way to go.
DnPRK is offline  
Old March 26, 2020, 07:54 AM   #13
9x19
Senior Member
 
Join Date: October 15, 1998
Location: Sherman, TX USA
Posts: 3,557
**clarity**

Thanks
__________________
Make mine lean, mean, and 9x19!

Last edited by 9x19; March 26, 2020 at 10:13 PM.
9x19 is offline  
Old March 26, 2020, 03:12 PM   #14
9x19
Senior Member
 
Join Date: October 15, 1998
Location: Sherman, TX USA
Posts: 3,557
Here are some pictures to illustrate how the hammer pin in a standard AR fire control group is retained.

Hammer with spring and pin installed - note the boss and coil over on each side extends all the way to the receiver walls (the pin ends will be inside the receiver walls):


Piano wire hammer pin retainer shown at bottom of hammer


Piano wire hammer pin retainer (Shown inside cut in center of pin tunnel) - wire bears against center grooove of hammer pin and keeps pin in place in receiver


I hope this helps...
__________________
Make mine lean, mean, and 9x19!
9x19 is offline  
Old March 26, 2020, 03:45 PM   #15
Onward Allusion
Senior Member
 
Join Date: November 17, 2009
Location: Back in a Non-Free State
Posts: 2,850
Simple fix - a single tiny drop of hot glue from glue gun. I did that for a couple of my Glocks and that fixed the problem for good.
__________________
Just keep this in mind the next time humanity fails you - "designed by clowns, who in turn are supervised by monkeys."
Onward Allusion is offline  
Old March 26, 2020, 05:06 PM   #16
Nodak1858
Senior Member
 
Join Date: September 7, 2009
Location: N. Dakota
Posts: 258
Quote:
IIRC, a self contained drop in trigger group does not allow the hammer spring to hold the pins in. If this is fact one of the “cartridge” type trigger groups. Like the POF units i use, some type of anti-walk pins should be used.
This
You'll need anti-walk pins for this style, I have used a few varieties, pick one most work fine.
__________________
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.
Nodak1858 is offline  
Old March 26, 2020, 05:19 PM   #17
smee78
Senior Member
 
Join Date: July 14, 2008
Location: South Carolina
Posts: 2,653
Here is a picture from one of my AR's showing the spring legs up over the pin.

I also would just pick up a set of anti-walk pins to be sure the pins don't drop, its cheap insurance in your case.
Attached Images
File Type: jpg FCG 1.jpg (38.9 KB, 14 views)
__________________
We know exactly where one cow with Mad-cow-disease is located, among the millions and millions of cows in America, but we haven't got a clue where thousands of illegal immigrants and terrorists are
smee78 is offline  
Old March 26, 2020, 06:08 PM   #18
ECM4
Member
 
Join Date: February 18, 2019
Location: West Virginia
Posts: 38
Quote:
Originally Posted by DnPRK View Post
ECM4, I assume you installed a Timney drop-in hammer/trigger group.

Personality, I wouldn't trust two tiny set screws to hold the hammer and trigger pins in place. KNS pins or similar are the way to go.
I installed AAO manufacturing drop in trigger. About the 3rd of the price of a higher end timney. Went out and shot a few hundred rounds through it today and pins never moved. I will be getting some new pins to make sure but nothing can move. For the price these triggers feel great. We will find out if they still work after thousands of rounds down the road but for now can’t be happier with a $90 trigger.
ECM4 is offline  
Old March 26, 2020, 06:28 PM   #19
Nathan
Senior Member
 
Join Date: July 1, 2001
Posts: 4,910
Elftman makes the best, IMO. LINK

I use these on all my AR’S.
Nathan is offline  
Old March 26, 2020, 07:41 PM   #20
9x19
Senior Member
 
Join Date: October 15, 1998
Location: Sherman, TX USA
Posts: 3,557
Smee78,

Thanks, yes your picture shows the hammer spring legs retaining the trigger pin. The trigger bosses on each side have their top half milled away so those spring legs can find the groove in the trigger pin.
__________________
Make mine lean, mean, and 9x19!

Last edited by 9x19; March 26, 2020 at 10:13 PM.
9x19 is offline  
Old March 26, 2020, 07:51 PM   #21
44 AMP
Staff
 
Join Date: March 11, 2006
Location: Upper US
Posts: 20,972
Quote:
The hammer spring legs do rest atop the trigger pin to prevent it walking, but there is no way the forward legs of the trigger spring will go over the hammer pin.
MY bad. You are right, and I was wrong, I had "hammer" and "trigger" springs somehow swapped in my head. The HAMMER SPRING keeps the TRIGGER PIN from walking out, not the other way around as I mis-stated it. I have removed the incorrect information.
__________________
All else being equal (and it almost never is) bigger bullets tend to work better.
44 AMP is offline  
Old March 26, 2020, 10:15 PM   #22
9x19
Senior Member
 
Join Date: October 15, 1998
Location: Sherman, TX USA
Posts: 3,557
Edited my posts as well to remove further confusion... thanks for clarifying.
__________________
Make mine lean, mean, and 9x19!
9x19 is offline  
Old Yesterday, 08:34 AM   #23
rickyrick
Senior Member
 
Join Date: March 15, 2010
Posts: 7,499
My POF trigger came with the KNS anti-walk pins free as a package deal a couple of years ago.
rickyrick is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:27 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.08265 seconds with 10 queries