Several years ago I had this rifle made.

It's got a Geissele S3G trigger in it.
It's functioned perfectly fine since I got it until recently.
(Note: it's got a fairly low round count - maybe 1000 absolute high end)

Recently (past couple months) it's begun having firing issues.
Sometimes (rarely) it will function normally. Most times you get between 1-3 rounds down the barrel with one trigger pull and ending with a light primer strike.

Things we've tried:

Swapped in a known good full BCG.
Swapped in a known good buffer & spring.
Swapped in a heavier buffer & new spring.

Issue persisted through all of that.
So I contacted Geissele and told them what's going on.
They sent a trigger spring kit for me to try.

We installed the new springs and issue persisted still.
Contacted Geissele again and they told us to send them the trigger to look at.
A week or two later they sent us a completely brand new trigger to install.

We installed the new trigger and issue persisted still.

We then tried the same steps as before with the new trigger (BCG & buffer parts).
We tried every combo possible of all those things - issue persisted.

I then took the "problem" upper and put it on a different lower - full mag dump - zero issues.
I then took the "problem" lower and put it on a different upper - full mag dump - zero issues.

What the hell am I missing here?

Multiple rounds firing along with dead trigger typically indicate you have a worn or defective disconnector. The upper really shouldn't factor into the equation.

Sounds like the recoil spring or it needs an H3 buffer. You got bolt bounce.

quote:

Originally posted by 4sigman:
Multiple rounds firing along with dead trigger typically indicate you have a worn or defective disconnector. The upper really shouldn't factor into the equation.

The whole entire trigger was replaced though - that includes the disconnector.

quote:

Originally posted by Mars_Attacks:
Sounds like the recoil spring or it needs an H3 buffer. You got bolt bounce.

The replacement buffer we used is an H3.

Have you tried a milspec hammer and trigger?

It still sounds like the lugs aren't locking up in the barrel extension.

Burst fire with soft primer strikes sounds like the hammer spring is on backwards.

quote:

Originally posted by powermad:
Burst fire with soft primer strikes sounds like the hammer spring is on backwards.

Doublechecked and the spring looks fine.

Testing the upper on a different lower without issues and the lower on a different upper and both with proper functioning is odd. Maybe you have a tolerance stacking issue with the original upper/lower pair. Maybe do some measurements to be sure both receivers are in tolerance from mating face of lower to trigger pin holes, and the upper to the bolt bore.

quote:

Originally posted by pbslinger:
Testing the upper on a different lower without issues and the lower on a different upper and both with proper functioning is odd. Maybe you have a tolerance stacking issue with the original upper/lower pair. Maybe do some measurements to be sure both receivers are in tolerance from mating face of lower to trigger pin holes, and the upper to the bolt bore.

This is what it sounds like to me.

quote:

Originally posted by creslin:

Recently (past couple months) it's begun having firing issues.
Sometimes (rarely) it will function normally. Most times you get between 1-3 rounds down the barrel with one trigger pull and ending with a light primer strike.

1-3 rounds with one trigger pull? Does this have a FRT in it?

quote:

Originally posted by creslin:

quote:

Originally posted by Mars_Attacks:
Sounds like the recoil spring or it needs an H3 buffer. You got bolt bounce.

The replacement buffer we used is an H3.

There's H3 buffers, then there's H3 Tungsten buffers. You gotta have the H3 Tungsten slug buffer. Just a heavier buffer won't work.

If all else fails, the KynShot hydraulic will do the trick if you got some odd rifle and gas combo.