Trigger Pin Troubleshooting

[Ranger86]

Good morning,
I have a BCM lower with a Geissele SSA trigger. The lower was purchased from Grant with the SSA already installed. The lower is NFA registered and setup with a 10.5” piston upper and only used suppressed. Approximately 1500 – 2000 rounds through it before last weekend. No issues at the range, typically shooting 100 -200 rounds per session.

Last weekend I took Defensive Rifle at the Sig Academy. The rifle performed well, except the Trigger Pin kept creeping out. I had to push it back in about 6 times throughout the weekend. There was enough tension on the pin that I could not push it back in or tap it back in with a piece of brass until I lowered the hammer. It would then push back into position easily with my finger.

My troubleshooting plan is to remove the trigger. I hope to borrow a set of pin gauges to check the diameter of the holes and use calipers to measure the pin. I will also confirm the trigger was correctly installed (I have not removed it yet). I expect one of those 3 things to be incorrect, identifying the problem.

I searched the forum for this issue and found some circa 2009 posts, but nothing current. Unless improper installation is to blame (I doubt it since the trigger pull is exactly like my other SSA rifle), I am wondering if KNS trapped pins would be an acceptable solution if the lower hole is too big. I thought I read somewhere that they were not recommended for the Geissele triggers.

Is my troubleshooting plan comprehensive enough? Is there something else that could cause this that I should look for? Any advice would be welcome.

Thank you,
Mike

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[SteveL]

A trigger pin walking out is normally caused by improper installation of the hammer spring. The legs of the hammer spring should rest on top of the trigger pin. The trigger pin should have a notch in one or both ends. The legs of the hammer spring rest in that notch and this is what keeps the trigger pin in place.

[556BlackRifle]

Send a picture looking straight down into the lower receiver over the trigger to confirm what SteveL said above. 99.9% chance that's what it is.

[Ranger86]

Thank you, I'll add a picture after work today.

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[Hammered_Pair]

KNS kit won't hurt either.

[MistWolf]

Bill Geissele has warned against the use of the KNS pins with his precision triggers. The pins provided with G triggers should be used as they are slightly over sized for a better fit and function.

Fix the problem and the KNS pins won't be needed.

[Ranger86]

I know, I have not cleaned it since day 2 of class, I'll clean it tomorrow. The picture should still show spring placement.

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[Ranger86]

It does look like the leg of the spring is wrong. Correct?

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[Ranger86]

2nd pict

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[26 Inf]

The legs of the hammer spring should be over the the trigger pin.

The picture at the head of this article shows it pretty good: https://www.itstactical.com/warcom/f...-installation/

Don't sweat it, we've all done something similar.