9mm AR problem

[crossgun]

Guys need some help and direction. Running a 9mm Rock River with the new Timney trigger. Problem is that the trigger is not always resetting. I have reliable extraction and feeding but at times the trigger has not cocked or reset it's self and is in the forward position.

If the hammer is following the bolt forward why dose the gun not double ?

Is this mainly a trigger problem or is something else wrong ?

With 100% extraction there should be amble time and distance for the trigger to rest.

The gun has the 9mm buffer in it. Should I try a lighter H buffer to make sure that the bolt is moving back far enough or possibly go the other way.

Your thoughts would be appreciated prior to calling Timney

[Joseywales]

Qustions:

1. Did you build this lower? The problem could be the hammer (needs to be a 9mm hammer). Secondly, make sure that your trigger mechanism has all the proper springs in it and in the right places. Make sure you are using a 9mm buffer (shells should be ejecting and next round loading).

2. Need to use correct firing pin.

3. Bolt is likely not going back all the way. Try to use P+ ammo and see if it works.

3. Check how far buffer extends out of tube. It may be catching. Make sure you used correct buffer spring.

4. Make sure mag well is at correct height and not interfering with ops.

[SHIVAN]

Put a standard trigger group in and see how it runs.

[Robb Jensen]

Keep your 9mm buffer.

If the hammer is following it can double but doesn't me it always will (its a timing issue, if it follows sometimes it won't hit as hard). Call Timney, we've had some trouble with some Timney AR triggers hammer following right out of the box after install. On a friends 9mm RRA I installed a Timney and it failed the function test (without evening shooting the rifle), on safe it wouldn't fire. Moved the selector to fire and pulled the trigger, hammer fell. Held the trigger and cycled the bolt (to reset the trigger), released the trigger and he hammer fell again (NOT GOOD!). I removed the Timney trigger and replaced with a RRA 2stage match trigger & used Gen2 KNS pins which works fine.

Consider using the KNS pins (which are stainless) or getting a stainless hammer pin. 9mms are hard on hammer pins.

[Longboat]

I agree with Shivan.. Put a standard FCG in and see what happens.

As GotM4 said, you can have a follow home and not have a primer detonation. Not all that unheard of especially with the DIAS if they are not timed right.


I don't like to start swapping major parts until I have it running at peak performace with original equipment. It is much easier to determine what the problem is when you know it worked form the start.

[crossgun]

gotm4

Thanks for the great info. As always you are well ahead of the curve and dialed in. Spoke with John at Timney for about an hour the other night. He is great to deal with. We both had gun parts and calipers lying all over the place to try and figure out the problem from both ends. Seems they are fighting the tolerance issue a bit in the variation of lowers from the numerous makers.

Trigger is on its way back to him. He was very honest and upfront about the issues you mentioned. Seems they are already a Rev. past the one I had and constantly working to refine their product.

Thanks for the info on the KNS pins. Will do!

How can I run a RR 2-stage trigger in my 9mm? Don't I have to modify the bolt in some fashion? Just tried putting the bolt on another lower equipped that way and the bolt would not go all the way forward.

[Snake RAH]

Just curious here, but why do you want a match trigger in a 9mm gun?

[crossgun]

snake RAH

Building a fun little games gun. The stock Rock River 9mm trigger just SUCKS!
The rifle will be used for pistol caliber 3-gun shoots as well as some steel plate matches.

I need it to be able to run hard and fast as it will always be on the clock.

Why not, it makes the CDI factor really high. Especially when I add the KNS pins.

[LukeMacGillie]

I understand the CDI factor, so take my comments for what they are worth and drive on with CDI

My agency is one of the last in the world to still use the 9mm SMG. Other than the beefed up bolt catch, the mag well block et al and the heavier buffer everything else is no different than the internals of a M4A1.

I am trying to push the issue of the stainless FCG pins, as that is what I replace more than anything else, also the barrels tend to come loose unless you put in a pin thru the delta ring and disconnectors tend to get a dimple in just a few hundred rounds.

Like I said I understand CDI, but try a modied M4 hammer and disconnector. You might be plesently surprised.

[DrMark]

Just curious here, but why do you want a match trigger in a 9mm gun?

I'm not trying to answer for him, but it seems the Timney is not marketed as a match trigger. Timney has responded to inquiries in threads on various board that this is a trigger intended for hard use, providing durability and reliability.

There is a market for a duty-rated, hard-use trigger that provides a shorter pull, reduced creep, and a crisper break than the USGI trigger. Time will tell if the Timney is such a trigger.