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MasterYong
12-03-2009, 10:45 AM
I've used the search (using google, not the "search feature" on this site. blech.) I just wanted to say that outright as I know this has been asked.

I have a trigger pin on an AR that's walking out when I shoot it. The hammer spring legs are where they should be, sitting on the trigger pin which as I understand it is supposed to set in the groove on the trigger pin and hold the pin in place.

I never noticed this happening before on this rifle, but I'm in AZ right now and have been rapid-firing full-cap mags through it for the first time so I think that's what's causing it, the increased rate and volume of fire in desert shooting from my standard norcal range shooting.

I know there are anti-walk pins. I'd like to fix this without having to purchase those.

The LPK is either stag or RRA, I can't recall which on this build and I've bought both brands for my builds so it's one or the other.

I pulled the FCG, and the trigger pin looks like the indentation for the hammer spring legs is just as deep as my other builds, which do not walk. Odd.

I have read threads here that suggested using a small file to make the indentation in the trigger pin a little deeper. It just seems like doing something like that is an invitation to have the pin break during firing.

So, other than anti-walk pins, what's everyone's preferred method for fixing this kind of issue? What are my options?

Or is there something else I may be missing?

Any and all input would be greatly appreciated. To give a little more background this is not my first build, nor is it a new build (had probably 600 rounds through it with 10 rd mags before I took it to AZ). I'm 100% certain I put it together correctly, I've build 4 other ARs without any real problems.

Thanks in advance for any help!

sirnonz
12-03-2009, 10:47 AM
for quick fix i just used a little bit of tape on both sides until i forked out the money for anti walks.

MasterYong
12-03-2009, 10:52 AM
for quick fix i just used a little bit of tape on both sides until i forked out the money for anti walks.

MacGuyver-

Thanks for the tip. I'd definitely thought of that, but I'd like something that doesn't involve bubble gum, an avacado, and a paperclip.

:p

(I admit that at this point I've been shooting ten rounds, pushing the pin back in, shooting ten more, etc. If I don't get too close to 20 rounds it doesn't completely walk out of the hole. Funny thing is, this never happened in CA and I don't recall ever having to push the trigger pin back in, even after 100 rounds at the range.)

ETA: C'mon guys! It's been an hour! No awesome fixes yet? Ya'll are slippin!!!! :D

krzgoat
12-03-2009, 11:48 AM
Sorry no fix that I know of other than the anti-walk pins which I have on mine.

coop44
12-03-2009, 11:50 AM
get a new pin, they can be had in 2 diameters .153 or .154, cut the retention grooves deeper, or wider. If you have a drill motor or press this is pretty easy.

Or you can reparkerize the pin and add .001-.0015 to it.

Or, you can keep throwing money at it.

wash
12-03-2009, 12:18 PM
Is the step on the side of the trigger deep enough?

Did you try a 15 minute trigger job? If you bent the hammer spring the wrong way it might not engage the notch properly.

Are you hammer spring legs in the right place?

I would assemble it, pull the trigger (don't let the hammer slam forward) and see what's going on.

I hope you figure it out.

bigcalidave
12-03-2009, 12:25 PM
Why DON'T you want the kns pins? They work great.

MasterYong
12-03-2009, 12:26 PM
Is the step on the side of the trigger deep enough?

I don't understand this question, to be honest. What step are you referring to? I'm not at work so I can't look. Can you be more specific or point me to a pic of what you mean?

Did you try a 15 minute trigger job? If you bent the hammer spring the wrong way it might not engage the notch properly.

Never bent the hammer spring the wrong way, but thanks for the suggestion!

Are you hammer spring legs in the right place?

Yes, but thanks!

I would assemble it, pull the trigger (don't let the hammer slam forward) and see what's going on.

I always function-check the rifles before firing. This one is g2g and shoots fine, it's just after a certain number of rounds the pin walks out enough in one direction that the other side drops into the lower and the rifle no longer functions. I've tried to recreate this by doing the function-check about 100 times while watching TV, but the pin doesn't budge. I think it's the recoil that causes it to walk...

I hope you figure it out.

So do I LOL. Thanks again.


In bold.

MasterYong
12-03-2009, 12:28 PM
Why DON'T you want the kns pins? They work great.

I don't feel like spending the money on it. Funny thing is it's not the money that's the issue, it's my extreme thriftiness... I'd rather use the parts I have if I can. If I can't find a good solution I'll definitely just buy the anti-walk pins. That being said where's the best place to get the pins? I usually get most of that small stuff from riflegear...

ar15barrels
12-03-2009, 12:36 PM
Hammer spring is installed backwards.

wash
12-03-2009, 12:36 PM
If you look at the trigger, the tube that the pin slides through has steps on both sides. That allows the hammer spring legs to engage the grove on the trigger pin. If it's not deep enough or ground at the wrong angle, the leg of the hammer spring might not get in to the grove.

Also, if you have your upper on when you try to look at the trigger mechanism you won't see much. Try it with the upper off.

aermotor
12-03-2009, 12:44 PM
Antiwalk pins are incredibly fugly... I'd suggest trying another pin as someone else said.

wash
12-03-2009, 12:45 PM
Hammer spring is installed backwards.
I didn't know that was possible.

MasterYong
12-03-2009, 12:46 PM
Hammer spring is installed backwards.

Nope. Thanks though, I could see how that could cause the same issue...

If you look at the trigger, the tube that the pin slides through has steps on both sides. That allows the hammer spring legs to engage the grove on the trigger pin. If it's not deep enough or ground at the wrong angle, the leg of the hammer spring might not get in to the grove.

Also, if you have your upper on when you try to look at the trigger mechanism you won't see much. Try it with the upper off.

I've def looked at it with the upper off (first thing I did out in the desert when it started happening and several times since).

Thanks for explaining the trigger part. For some reason it didn't occur to me that the part may be too high. It would be pretty hard to tell with the parts in the lower too. I'll remove the FCG again and put the parts together in my hand and see if the step is low enough for the spring legs to engage the pin. I can fix that easy with a dremel or file I think, if that's the problem.

sirnonz
12-03-2009, 1:08 PM
i have the dmps anti walk pins, it's a lot cheaper than the KNS ones

bombadillo
12-03-2009, 1:20 PM
KNS pins have been great for me!

shooting4life
12-03-2009, 1:21 PM
You cannot be a true operator unless you have kns pins!! I have them on my dedicated ar22!!!

http://i630.photobucket.com/albums/uu30/shooting4life/jordangunstuff012.jpg

http://i630.photobucket.com/albums/uu30/shooting4life/jordangunstuff011.jpg

Don't Drool to much over the value pack now

MasterYong
12-03-2009, 1:30 PM
You cannot be a true operator unless you have kns pins!! I have them on my dedicated ar22!!!

http://i630.photobucket.com/albums/uu30/shooting4life/jordangunstuff012.jpg

http://i630.photobucket.com/albums/uu30/shooting4life/jordangunstuff011.jpg

Don't Drool to much over the value pack now

Not gonna. I'm in AZ. Near Glendale. Cabela's has had thousands of boxes of that in stock for months for $18.99 each. :p

ar15barrels
12-03-2009, 1:39 PM
I didn't know that was possible.

Yep.
It causes trigger pins to walk out.

ar15barrels
12-03-2009, 1:41 PM
If you look at the trigger, the tube that the pin slides through has steps on both sides. That allows the hammer spring legs to engage the grove on the trigger pin. If it's not deep enough or ground at the wrong angle, the leg of the hammer spring might not get in to the grove.

This is the 2nd most common cause of trigger pin walk.

gregr266
12-03-2009, 2:09 PM
Ive got the same issue....how do you tell if the spring is installed backwards

creampuff
12-03-2009, 2:23 PM
Ive got the same issue....how do you tell if the spring is installed backwards

The analogy I would make is: if the long leg of the spring is like a roll of toilet paper coming over the top relative to the face of the hammer, then it is good. If the roll of toilet paper is coming under, relative to the face of the hammer, then it is backward.
http://i76.photobucket.com/albums/j36/creampuff464/springs.jpg

wash
12-03-2009, 2:32 PM
That picture shows the step I mentioned, but it's a trigger spring.

The one that can cause problems is the hammer spring.

ar15barrels
12-03-2009, 3:06 PM
Ive got the same issue....how do you tell if the spring is installed backwards

http://i76.photobucket.com/albums/j36/creampuff464/springs.jpg

run8
12-03-2009, 3:11 PM
Hey Master Young were going to badger you until you buy those KNS pins ;-)

creampuff
12-03-2009, 3:19 PM
That picture shows the step I mentioned, but it's a trigger spring.

The one that can cause problems is the hammer spring.

I can't believe I did that !! Fixed!

LOL, AR15 Barrel knows my pictures better than I know my own pictures. :)

thanks

five.five-six
12-03-2009, 3:21 PM
Hammer spring is installed backwards.

^ that

ar15barrels
12-03-2009, 3:28 PM
LOL, AR15 Barrel knows my pictures better than I know my own pictures. :)

Google images> "AR-15 hammer spring installation" ;)

Though it is a good picture.
Mind if I snag it for my technical pictures folder?

www.ar15barrels.com/tech

bohoki
12-03-2009, 5:03 PM
i got the ones with the little clips on mine once it starts happening it just doesn't stop
mine always walked out to the leftnever toward the ejection port it was weird like they were possessed by the devil

bwiese
12-03-2009, 5:07 PM
I have a trigger pin on an AR that's walking out when I shoot it. The hammer spring legs are where they should be, sitting on the trigger pin which as I understand it is supposed to set in the groove on the trigger pin and hold the pin in place.

You likely have substandard spring(s) holding the pins. Get new springs. I see this on rifles using "no-name" gunshow parts kits.

I've always had good luck with Bushmaster or Armalite springs.

The hammer & trigger pins may also have some issue - perhaps too much coating on the pin groove(s) such that it's easy for the spring leg(s) to pop out of the groove. Use some BonAmi and moist dental floss and you can 'clean up' the groove and make it more defined (i.e, spring legs will seat more deeply in the groove.) Doesn't take much.



I know there are anti-walk pins. I'd like to fix this without having to purchase those.

Don't need those. Those are for exceptional situations/excessive wear, etc.

VaderSpade
12-03-2009, 5:45 PM
Hammer spring is installed backwards.

We have a winner.

Check it again while looking at the picture above.

ar15barrels
12-03-2009, 7:23 PM
We have a winner.

Check it again while looking at the picture above.

When the hammer spring is installed backwards, the legs of the spring don't engage the slots in the pin because the legs are going across the trigger at an angle instead of straight across the top where the cuts in the trigger would let them lay in the slots on the pin.

MasterYong
12-04-2009, 6:10 AM
You likely have substandard spring(s) holding the pins. Get new springs. I see this on rifles using "no-name" gunshow parts kits.

I've always had good luck with Bushmaster or Armalite springs.

The hammer & trigger pins may also have some issue - perhaps too much coating on the pin groove(s) such that it's easy for the spring leg(s) to pop out of the groove. Use some BonAmi and moist dental floss and you can 'clean up' the groove and make it more defined (i.e, spring legs will seat more deeply in the groove.) Doesn't take much.





Don't need those. Those are for exceptional situations/excessive wear, etc.

The hammer spring came with ether a Stag or RRA LPK. I assembled my rifles back in CA using one brand or the other for each rifle and I just don't remember which brand went in this particular rifle. Parts kits came from Addax and riflegear so I'm assuming the brands are correct.

Randall-

The hammer spring was installed correctly. I did swap it with another hammer spring though and lo and behold it didn't walk at all out in the desert shooting after work yesterday. The other hammer spring also came from either a Stag or RRA LPK. I compared the two springs before replacing the "bad" one and the "bad" one's legs were at a much more extreme angle than the "good" one.

Guess I'll chalk it up to a bad part (though not that bad, the rifle functioned, just not for long LOL). At least it's a cheap part.

Thanks for pointing me in the direction of the hammer springs guys!

coop44
12-04-2009, 8:02 AM
Do you really think all of the parts in your lpk came from the same place? If so, got a great bridge for you in new york, brooklyn I think.Bargain price, act now.

MasterYong
12-04-2009, 8:07 AM
Do you really think all of the parts in your lpk came from the same place? If so, got a great bridge for you in new york, brooklyn I think.Bargain price, act now.

I didn't realize it was common knowledge that manufacturers like Stag and RRA just threw a bunch of garbage parts in a bag and sold it to customers, as you seem to think.

Seems much more likely to me that manufacturers like Stag and RRA would try their best to put high-quality parts in their LPKs, since those LPKs carry their brand on the package and one's experience with the LPK would affect their opinion of the brand. I realize that most (maybe all) of the manufacturers contract-out the manufacture of small parts.

There's no reason to be a *****. I never asserted that I thought all the parts in the LPKs were made by the company who's name is on the bag- but it seems generally accepted amongst AR owners that both these companies sell good LPKs.

glock_this
12-04-2009, 8:09 AM
Why DON'T you want the kns pins? They work great.

simple.. its $30.. have not needed them in my 2 builds. if I had issues, I would try a new $1 pin first (assuming the spring install is not the issue :) )

ar15barrels
12-04-2009, 8:36 AM
Do you really think all of the parts in your lpk came from the same place?

I didn't realize it was common knowledge that manufacturers like Stag and RRA just threw a bunch of garbage parts in a bag and sold it to customers, as you seem to think.

Whoa tiger, he did not say the parts were garbage.
He just said they are not all from the same source.

MasterYong
12-04-2009, 9:20 AM
simple.. its $30.. have not needed them in my 2 builds. if I had issues, I would try a new $1 pin first (assuming the spring install is not the issue :) )

+1

I think the anti-walk pins are really meant for folks in service who's weapons are either a lot more worn out (the holes in the lower) or folks whose weapons may be subject to that kind of use. I could be mistaken. While they may have other uses I'd rather make it work with the original pins. I did.

What's odd is that the new hammer spring has much more power to it than the old one due to the old one being set at the wrong angle (maybe at the factory?)- I'm surprised that with such a light strike in comparison to the new spring that the old spring still got the hammer to strike the primer hard enough to fire- but it worked just fine other than the pin walking out. I've never had any failures on this build except this darn pin- which has since been fixed.

gregr266
12-04-2009, 12:16 PM
That's was my problem my we're in backwards that's guys I'll try it out this weekend

Bnaka75
12-04-2009, 4:06 PM
I have noticed my trigger pin did not seam secure and after reading this I find out that my hammer spring was installed backwards this whole time, thanks guys.

Tyrius
12-04-2009, 4:28 PM
+1 noob with a backwards hammer spring that only figured it out because of this thread. :rolleyes:

The worst part is that I distinctly remember installing it correctly the first time, and then trying to push it into the lower only to think, "Man, there's no way it's supposed to be that tight. I must have put the spring on wrong," and subsequently "fixing" it.

norcal-ar
12-04-2009, 5:09 PM
This is the 2nd most common cause of trigger pin walk.

whats the 1st most common problem?

ar15barrels
12-04-2009, 7:51 PM
whats the 1st most common problem?

Hammer spring installed backwards.