Trigger Pins Walk Out

[JsnSanko]

Aero Standard Lower with Enhanced Upper. Nice build. JP SCS. Standard BCG. Luth-AR MBA-1 buttstock. Ranier Arms Ultramatch 308 barrel. I am not the best shot, but not bad. It honestly is 1 MOA (5 shots) with about any load I have made with 175 SMKs and 4064 or CFE223. I have stopped load development due to a problem I found in the new build. I think this build is capable of less than what I have been able to do so far. Have about 150-200 rounds through so far. Cycles flawlessly.

So the problem. Every 15-20 shots the trigger pin moves out of the side to the point it disengages from the frame. Binds trigger up. It’s a Geissele SSA-E trigger.

What are the options? New lower, or larger pins?

 

[hlee]

Geissele will tell you to get a new lower. You could get anti-walk pins. But, Geissele will tell you that they are too soft and will eventually fail…

 

[dogman]

Did you make sure the legs of the hammer spring that extend toward the back of the receiver are on top of the trigger pin and not under it?

The spring legs hold the pin in place, unless you have something horribly out of spec.

 

[JsnSanko]

Yes I checked that. It still walks sideways.

 

[the monk]

I would ping Geissele and get them to send you new trigger pins just to check for tolerance stacking. If after receiving, installing and using the new pins you still have the same issue I would contact Aero for a new lower.

 

[thehun]

More than likely its an Aero problem however...with Geissele's QC mishaps as of late...who knows...as @the monk said...I'd follow his approach and see...if you don't want to deal with CS rep crap...just get some KNS pins and call it good...

 

[Ruff 364]

KNS PRECISION, INC. AR-15 GEN. 2 MOD. 2 NON-ROTATING PIN SET | Brownells

Identical function as the standard sets listed above, but with ultra-low-profile links that protrude even less above the receiver. Available with standard .154" diameter pins, oversized .155" pins, or .170" pins for large-pin receivers. SPECS: Car...

www.brownells.com

 

[bill_van]

Run some KNS pins. Solves several issues and tightens you the fire control group for a slightly better feel. I run them on everything mainly as a precaution. On my registered lowers as the replacement lowers would be in the thousands of dollars where a $20 set of KNS precludes any wear on the holes.

 

[the monk]

AR Triggers & Anti-Rotation Trigger Pins – School of the American...

Anti-rotation trigger pins are something we see on a lot of AR builds, but are they really necessary? Can they be causing more harm than good

www.arbuildjunkie.com

 

[Docsherm]

Get a new trigger. If that does not help then the KNS pins are the way to go.

 

[larryh128]

Aero Standard Lower with Enhanced Upper. Nice build. JP SCS. Standard BCG. Luth-AR MBA-1 buttstock. Ranier Arms Ultramatch 308 barrel. I am not the best shot, but not bad. It honestly is 1 MOA (5 shots) with about any load I have made with 175 SMKs and 4064 or CFE223. I have stopped load development due to a problem I found in the new build. I think this build is capable of less than what I have been able to do so far. Have about 150-200 rounds through so far. Cycles flawlessly.

So the problem. Every 15-20 shots the trigger pin moves out of the side to the point it disengages from the frame. Binds trigger up. It’s a Geissele SSA-E trigger.

What are the options? New lower, or larger pins?

K & S, they make a pin that is 1/2 thou oversize that works good but also pins that use a small machine screw in each side. They don't go anywhere.

 

[Milf Dots]

Ask Geissele to send you a new spring and pin.

 

[msgriff]

Hopefully you didn't get the large pin (0.170") SSA-E trigger. Standard pin is 0.154". You can measure the trigger/hammer pin holes using the shanks from a numbered twist bit set, then measure the shank with calipers/micrometer Not as accurate as pin gauges, but better than nothing. Hole spec is 0.1560" + 0.0015". A 5/32 bit is 0.1562" and should not pass through.

 

[1911hombre]

Hopefully you didn't get the large pin (0.170") SSA-E trigger. Standard pin is 0.154". You can measure the trigger/hammer pin holes using the shanks from a numbered twist bit set, then measure the shank with calipers/micrometer Not as accurate as pin gauges, but better than nothing. Hole spec is 0.1560" + 0.0015". A 5/32 bit is 0.1562" and should not pass through.

If he got the large pin it wouldn't fit. As in could not be assembled.

 

[msgriff]

If he got the large pin it wouldn't fit. As in could not be assembled.

Mil spec trigger pins would fit in a trigger designed for 0.170" pins. It would be sloppy, cause malfunctions and should be obvious.

 

[1911hombre]

Mil spec trigger pins would fit in a trigger designed for 0.170" pins. It would be sloppy, cause malfunctions and should be obvious.

Ok, so he buys a large pin trigger from Geissele by mistake and then when he gets it the supplied large pins won't fit in his lower, so he grabs some mil-spec pins laying on the bench and goobers it all together? That dog don't hunt.

 

[msgriff]

Ok, so he buys a large pin trigger from Geissele by mistake and then when he gets it the supplied large pins won't fit in his lower, so he grabs some mil-spec pins laying on the bench and goobers it all together? That dog don't hunt.

For all I know it was mislabeled or packaged. I'm just offering info. Thanks for your contribution.

 

[the monk]

Just call Geissele. They have fantastic customer service that I have used many times. You should not need anti rotation pins if everything is on spec.

 

[_Windrider_]

KNS PRECISION, INC. AR-15 GEN. 2 MOD. 2 NON-ROTATING PIN SET | Brownells

Identical function as the standard sets listed above, but with ultra-low-profile links that protrude even less above the receiver. Available with standard .154" diameter pins, oversized .155" pins, or .170" pins for large-pin receivers. SPECS: Car...

www.brownells.com

I use these in everything. They work.

 

[rpoL98]

Geissele will tell you to get a new lower. You could get anti-walk pins. But, Geissele will tell you that they are too soft and will eventually fail…

KNS Gen G pins are harder, ostensibly.

Right-To-Bear: KNS Gen G

in FDE

 

[Strykervet]

I have seen some beat to shit rifles with no finish and no bore left that don't have this problem...

None of my rifles have this problem.

I don't use KNS shit and Geissele will tell you not as well. Never needed adjustable gas blocks or any of the bandaids these companies come up with. I do use quality parts. IME, Aero (and Mega) refused to take responsibility for out of spec parts, said "it's impossible with our QC methods (edit: machining SOP)" --what the fuck ever, my calipers don't lie. Unless their QC methods included random placement of holes and diameters and shit. Switching to only KAC and Noveske lowers/uppers ended tolerance issues. No problems with LMT either.

You have some kind of tolerance issue or weak hammer spring IMO but without looking at it, it's kind of hard to say.

To figure out whether it's the trigger or lower (or something else) I'd put a basic stock AR trigger in it and see if it still does it and go from there.

 

[2aBaC̶a̶]

Replace the lower?
replace the trigger?
buy a new top of the line reciever set?
ffs, you guys are unbelievable.

$20 anti walk pins is the easy fix.

 

[Snuby642]

Got to wonder what force is moving a trigger pin out of the reciver in 20 shots?

Considering the times I went to qualify in military service, and the fact that the rifles provided by the armory were without a doubt the most worn out slop buckets available to mankind.

They did in fact not fall the fuck appart during qualification.

Is there not instructions saying the trigger pin is to be inserted in a specific direction ?





Maybe we just check that first.


Aside from that a few measurements would sort out gross error.

 

[Strykervet]

Replace the lower?
replace the trigger?
buy a new top of the line reciever set?
ffs, you guys are unbelievable.

$20 anti walk pins is the easy fix.

Shouldn't be "walking" any goddamn where in the first place.

Aftermarket and custom shit comes with aftermarket and custom problems. More aftermarket shit isn't the fix.

Quality parts also come with less issues, sometimes you get what you pay for. Not to say that Aero is junk but they do have some random fit issues I don't have with Noveske, etc.

Got to wonder what force is moving a trigger pin out of the reciver in 20 shots?

Considering the times I went to qualify in military service, and the fact that the rifles provided by the armory were without a doubt the most worn out slop buckets available to mankind.

They did in fact not fall the fuck appart during qualification.

Is there not instructions saying the trigger pin is to be inserted in a specific direction ?

Aside from that a few measurements would sort out gross error.

Right?

It's why I stand by going back to a GI trigger and working back until you find the problem.

Just a guess but I'd say it's an out of spec trigger pin that doesn't have a deep enough cut for the hammer spring to engage. But can't say without seeing it. That would be the most likely culprit. Or a weak hammer spring.

And no, the trigger pin generally has a cut on one side so the hammer spring will rest on it regardless of how it's installed.

One thing worth mentioning though now that I think of it, Geissele did sell some "special" trigger sets to Brownells some years back... These have a different retention method. It's been a while since I had one apart though so I can't say for sure that'd be the issue. It did use a special spring to retain either the hammer, trigger or both.

Again, stock GI trigger. If it works, then contact Geissele and request another pin or RMA the thing.

Almost everyone on here has a drawer full of these too. I may have given mine away already though... LPK used to ALWAYS come with 'em.

 

[Snuby642]

Every brand of trigger I have used had instruction on direction to insert pin.

Not being the most obstinate jerk around I blindly followed that instruction.

I always wondered if the free world would come to an imidiate screetching halt if I violated that procedure.

None of my pins have fell the fuck out and it appears my piece of the world is still rotating properly.

None of the instructions said put it in any direction you want we don't give a tiney little shit.

But who knows? I declined to test it not actually giving a good God damn which way it goes one way or another.

 

[rpoL98]

...

One thing worth mentioning though now that I think of it, Geissele did sell some "special" trigger sets to Brownells some years back... These have a different retention method. It's been a while since I had one apart though so I can't say for sure that'd be the issue. It did use a special spring to retain either the hammer, trigger or both.

...

that was the Brownells Geissele G2S-E. had a special circular spring that clipped on one side.

 

[Snuby642]

After researching this out the instructions may be archaic stemming from fa requirements?

I'm sure some of my pins only had one groove on the reciver side.

It apparently is easier to install some pins in the direction specified.

I'm also not going to ignor instructions provided to save on troubleshooting problems that shouldn't exist.

Edit: It costs nothing to turn the pin around. Lol

 

[hlee]

If you already have the lower and the trigger, the ‘low hanging fruit’ solution is the Geissele specific KNS pins and move forward. (I didn’t know these existed until I read it here.)

If you don’t have a lower, spending $$$ on a high quality lower can be well spent in un-experienced angst and heart burn.

But, for many, a sub $50 anderson lower and a $20 set of trigger pins is a problem free solution.

 

[2aBaC̶a̶]

Shouldn't be "walking" any goddamn where in the first place.

Aftermarket and custom shit comes with aftermarket and custom problems. More aftermarket shit isn't the fix.

Quality parts also come with less issues, sometimes you get what you pay for. Not to say that Aero is junk but they do have some random fit issues I don't have with Noveske, etc.



Right?

It's why I stand by going back to a GI trigger and working back until you find the problem.

Just a guess but I'd say it's an out of spec trigger pin that doesn't have a deep enough cut for the hammer spring to engage. But can't say without seeing it. That would be the most likely culprit. Or a weak hammer spring.

And no, the trigger pin generally has a cut on one side so the hammer spring will rest on it regardless of how it's installed.

One thing worth mentioning though now that I think of it, Geissele did sell some "special" trigger sets to Brownells some years back... These have a different retention method. It's been a while since I had one apart though so I can't say for sure that'd be the issue. It did use a special spring to retain either the hammer, trigger or both.

Again, stock GI trigger. If it works, then contact Geissele and request another pin or RMA the thing.

Almost everyone on here has a drawer full of these too. I may have given mine away already though... LPK used to ALWAYS come with 'em.

I agree that they should NOT be walking and there is an obvious issue but unique issues do sometimes require unique solutions. he can troubleshoot and chase the problem or solve it one and done.

I would personally find the root issue because I just want to know but in the end anti walk pins are probably the solution anyways so thats what I reccomend.

he could have a large pin trigger and small pins but I I have doubts he would get this far without other issues.

1) make sure you dont have large pin trigger.
large is 11/64"
small is 5/32"
2) make sure trigger and springs are installed correctly. pin groove lines up with slot and spring leg falls in it. the pin should not move freely.

 

[rpoL98]

Did you make sure the legs of the hammer spring that extend toward the back of the receiver are on top of the trigger pin and not under it?

The spring legs hold the pin in place, unless you have something horribly out of spec.

^^^ This ^^^

the leg of the hammer spring (the really stiff spring), snaps into the exposed groove of the trigger pin, and should prevent the trigger pin from moving sideways. not sure how that spring could jump out of the groove...

also, the reason you install the hammer pin with the smooth end first, is to make it easier to get past the J-spring that's internal to the hammer.

 

[FatBoy]

I had this with a Jewell SR trigger. For years every 15-20 shots I reached up and pushing the pin back with my index finger. Late 90s DPMS Factory SR with Jewell added by P.O.

One day I got fed up and was going to switch to a Geissele SR trigger with the new barrel. I was talking to my buddy who does all my smith work and was profiling and chambering the new barrel. He looked at it and said nothing wrong. Here, use another pin. 20 seconds and $.20 fixed the fucking problem. Zero issues since.

Sometimes shit just doesn’t fit like it should. If it’s all together properly you may try a different pin. If your in a shop with a bin, look for one with the deepest/widest grooves you can find. May be that simple.