GAP-10/Geissele trigger malfunction (Easy Fix?)

[fastrider777]

GAP-10
.308
2 stage Geissele trigger

Last weekend during the post range inspection/wipe down/placing in gun safe, after my third trip to the range with my GAP-10 in .308, I noticed the anti-rotation pin had loosened up and was hanging from the screw on the left side of the receiver. I grabbed the correct size torx bit, placed it into a screwdriver and corrected the situation. I checked the other side and gave it a slight twist to tighten evenly.

I didn't crank on anything, only making sure everything was snug. (No loctite, no funny business)

With no magazine in the receiver, I cycled the charging handle several times, cycled the safety several times and making sure it wasn't loaded, I dry fired the gun and put it away.

The rifle had 140 rounds through it after 3 trips to the range.

This morning I went to the range and set up my station, when live fire began, I inserted the magazine, hit the bolt release and took aim. As I pulled the trigger for my first shot of the morning, I felt the first stage and when I squeezed the trigger to fire, it didn't break. It was stuck.

I flicked the safety to "ON." Dropped the mag and ejected the round. While cycling the safety back and forth, I was looking at the trigger and saw it move forward to the reset position. I reinserted the mag, hit the bolt release, clicked the safety off, aimed and pulled the trigger. The round fired, ejected and I thought that was just a weird thing, but looks like it cleared it's self up.

Went to fire round number 2 and the whole process started all over.

My questions are.....

Did this trigger get out of the proper adjustment?
Is this something I can just re-adjust using the instruction manual from Geissele?
Should I take it to a gunsmith locally?
Do I need to send it back to GAP?

Here is the rest of the important information:

No adjustments of the trigger have been made to it since I received it from GAP.

I cleaned the gun before firing it, using all BoreTech tools and supplies, including their bore guide, coated cleaning rod, bore cleaner and lube.

I cleaned the gun after the third trip to the range (140 rounds...early, but I thought it was a small compromise to over-cleaning)

I cleaned the upper separated from the lower. Nothing fell into the lower receiver.


I appreciate any suggestions and solutions.... I am also prepared for the sarcasm, so bring it on.

 

[arnie19]

I would loosen the pins back up and see if it operates then .The only problem I had was when putting in a custom trigger as the hammer was rolled back to full cock it would hit and bind on the front of the opening it sets in and a little trimming of the lower with a Dremel took care of that .

 

[hdbiker1]

My question is, did GAP put the anti rotation pins on? The reason I ask is Geissele specifically states not to use them. I'm sure that if GAP installs them, they must do some special magic to them.

 

[fastrider777]

I would loosen the pins back up and see if it operates then .The only problem I had was when putting in a custom trigger as the hammer was rolled back to full cock it would hit and bind on the front of the opening it sets in and a little trimming of the lower with a Dremel took care of that .

Thanks, I will of course try that before anything else.

 

[fastrider777]

My question is, did GAP put the anti rotation pins on? The reason I ask is Geissele specifically states not to use them. I'm sure that if GAP installs them, they must do some special magic to them.

The pins were installed at GAP.

That was the very first thing they said at the LGS that did the FFL. "These pins are not approved for use with this trigger."

 

[fastrider777]

I would loosen the pins back up and see if it operates then .

Wow..... Now I see why these pins are not approved for use with this trigger. As soon as I loosened the screws-----To a point where there was absolutely no tension to hold the screw from rotating, the trigger "clicked" and operated without problems.

Obviously, they've got to go. I have a couple of lower parts kits sitting around for another AR15 I built last year, I can steal the pins from there, correct?

 

[hdbiker1]

I'd get a hold of Geissele and request a set of pins. I believe they are slightly oversized to fit snugly into your lower unless your lower is slightly worn or slightly overspec.

 

[fastrider777]

I'd get a hold of Geissele and request a set of pins. I believe they are slightly oversized to fit snugly into your lower unless your lower is slightly worn or slightly overspec.

I contacted GAP explaining the situation and requesting a set of pins. I figure they must have a couple of hundred sets laying around since they come with the triggers but don't use them. Just on hold until someone answers my email. If I can't get them from GAP, I will contact Geissele.

In the original question, I had stated the gun was brand new, not worn, and I would hope/guess it's in spec.

Thanks for all the replies.

 

[arnie19]

I bought a set of the pins that use little cap head screws to keep them from sliding out .I didn't use them because you have to ream the holes in the lower and the trigger and hammer to a larger size .I hope they didn't do this to yours .

 

[BigBlue&Goldie]

Were they KNS pins or the JP style mentioned above?

 

[fastrider777]

Were they KNS pins or the JP style mentioned above?

KNS style, they were not oversized. The stock pins fit fine, but I noticed on the PDF instructions from Geissele that there could be a difference where the grooves are cut.

It's my plan to get a set of Geissele pins and replace the stock ones before bringing the rifle back out.

 

[BigBlue&Goldie]

That's really odd that GAP would use those as it's pretty common knowledge that Geissele specifically says not to use them. I heard some rumblings that Geissele is working with KNS to come up with a compatible set.

 

[toyotatrdt]

the geissele triggers come with there own set of pins, you have to use those pins or the adjustments doesn't work. also you should not mix the trigger pin with the hammer pin

 

[fastrider777]

Thanks again for all the great information

 

[Cobracutter]

That's really odd that GAP would use those as it's pretty common knowledge that Geissele specifically says not to use them. I heard some rumblings that Geissele is working with KNS to come up with a compatible set.

And its bullshit. Ive built guns and Geissele has a habit of providing undersized trigger pins. So much that I only use KNS anti's when running their triggers. Ive seen to too many times, especialy going from a mil-spec trigger/hammer/pins to the G.


OP check down inside the lower and make sure a primer or other debris did not find its way in there.

 

[jasonfaz]

Also check your grip screw. Ive seen some protrude just a hair too far into the lower - especially on this particular receiver set - which pushes up on the back of the Geissele units just enough that it causes your trigger not to reset consistently. In the cases ive seen where this is the issue, the gun will do exactly what yours is doing. It will fire once, but will not maintain reset function regardless of load used or other adjustments made to the gun.

 

[BigBlue&Goldie]

I'm not sure that I buy into the KNS pins being too "soft", but I do buy into the dimensional aspect. In the OP's scenario, he might have a tight hammer pin as he said it functions when the pin retaining screws are loosened to the point in which the pin is allowed to rotate in the receiver.

ADCO has a pretty good explanation on their website:

"<center>

Here is the deal on non-rotating pinsGeissele SSA pins are 0.1550" dia 0.0001. Holes in the trigger can be 5 tenths over Geissele pin size. Kns pins are either .154 or .1555. So they are either too loose or just about a metal to metal fit in Geissele triggers Geissele pins are chrome-moly steel that is rough turned, rough ground, heat treated and then centerless finish ground. They are a quality pin. Why do we not recommend KNS pins? One is that they are the wrong size. Can the smaller diameter pins work? Yes, but they are not the intended size and there can be a 'softer" break to the 2nd stage with them. But the biggest reason is that the KNS pins are soft. Sometimes when they are installed they pull up a burr that causes havoc with trigger operation. I get calls from frustrated customers where they are totally disappointed in their SSA because it either feels terrible or it hangs up. I spend all kinds of time on the phone wracking my brain trying to figure out what is going on and trying to work the customer through the problem. Finally, I ask the customer to send the trigger in (which I hate to inconvenience the customer with) and the issue is that the KNS pins are jamming the trigger up. A hammer or trigger pin that rotates maybe 1/8 of a turn with each shot, *might* wear through the hard anodizing after a million rounds. Let it rotate, it doesn't matter, its nothing to worry about. More FCG holes are damaged by people swapping the pins out every other week in an attempt to fix something that isnt broke. Steve"

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</center>

 

[355sigfan]

And its bullshit. Ive built guns and Geissele has a habit of providing undersized trigger pins. So much that I only use KNS anti's when running their triggers. Ive seen to too many times, especialy going from a mil-spec trigger/hammer/pins to the G.


OP check down inside the lower and make sure a primer or other debris did not find its way in there.

I used to use KNS pins with my Geissele triggers as well and then problems started to develop. Its best to listen to the manufacture of a product. So no its not BS stick with the pins Geissele provides.
Pat

 

[Cobracutter]

Except when Geissele ships out pins with it's triggers that are so loose, they rotate themselves out of the lower in less than a mag.

There are situations where both have merit.

 

[355sigfan]

Geissele does have larger pins for those with oversized or worn pin holes.
Pat

 

[Cobracutter]

0/10 there Pat

Multiple Mil-spec lowers including Colt Small Diameter and Various CMT Branded lowers. All New/unfired and triggers from different sources/time periods so it wasn't the same lot.

One would be an anominally, Two would be winning the lottery, Three..... Houston there's a problem.

 

[fastrider777]

And its bullshit. Ive built guns and Geissele has a habit of providing undersized trigger pins. So much that I only use KNS anti's when running their triggers. Ive seen to too many times, especialy going from a mil-spec trigger/hammer/pins to the G.


OP check down inside the lower and make sure a primer or other debris did not find its way in there.

I had hoped I was really clear about the problem I was having. Nothing has dropped into the trigger assembly.

If I tighten the screws, the way you think you need to tighten the screws (until it bottoms out on the pin) it causes the trigger to get stuck.

After I loosened the screws, the trigger jumped back to the reset position. Retightening the screws only caused the trigger to get stuck again.

I took out those pins, pushed in stock pins and everything worked fine.

I talked to Dustin at GAP today. He asked me if there was any sign of loctite on the screws, I said there was. I told him that they still came loose after 140 rounds. I told him exactly what I posted to the forum.

He is sending me a set of Geissele pins.

 

[fastrider777]

Also check your grip screw. Ive seen some protrude just a hair too far into the lower - especially on this particular receiver set - which pushes up on the back of the Geissele units just enough that it causes your trigger not to reset consistently. In the cases ive seen where this is the issue, the gun will do exactly what yours is doing. It will fire once, but will not maintain reset function regardless of load used or other adjustments made to the gun.

Thanks, I will also check that.

Still going to install the Geissele pins and go from there.

 

[cruze5]

Which trigger?

 

[Tahoe333]

My geissele SD3G will not function properly with geissele pins in a 80% lower due to the FCG holes being slightly misaligned. Correcting the crooked trigger hole will leave the hole egged/oversized.
After some research my options appear to be:
1) I can either try oversized anti walk pins <might not work with Geissele>
2) use a single hook FCG
3) use a cartridge style FCG.
*My first preference is to keep using my SD3G.