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tda1337
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Posted: 1/14/2012 6:31:06 PM
Hello to all.

To start off, after months of browsing as a guest, I finally decided to join ar15.com
I am an avid shooter, while being new to the sport. In less than one year I have collected 3 hand guns and an assortment of rifles. Including my favorite, my Stag model 8 ar15.

My third rifle, the CX4, was one I purchased for self defense prior to getting my handgun permit.
Purchased used, the only thing I saw wrong with it was the trigger was mushy.

Until recently, I have only had trigger problems and FTE (stove-piping sideways lol) when I use low powered ammo.
Being mechanically inclined, I replaced the trigger with a Sierra Papa trigger group.
It made the break nice and crisp, but one problem was persistent. The trigger continues to not always reset.

In Ar15s archives a user "Rustygun" also had this issue. He stated Beretta claimed it was the "transfer bar" (I'm assuming this is the trigger bar) and replaced it.
My CX4 9mm (92fs) was bought used so it isn't under warranty, and I would like to fix it myself if possible. I couldn't find rusty's outcome other than it came back ok.

I was wondering if the bar was bent, and I could replace it, or if something else obstructed its action.

Thank you in advance.

BTW, my current home defense weapon is a Sig 1911 Tacpak, which will get me to my Saiga .410 in the near future (on layaway lol). So this gun is more of a fun to shoot (bruises the shoulder for a 9mm) target gun now. Not in a rush to fix it.



forever4
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Posted: 1/14/2012 7:44:45 PM
I got a CX-4 when they first came out some years back. They don't have the best feel to the triggers but I did some minor work to mine and made it better. I may spring for the SP trigger as I love the rifle. Its not a difficult trigger group to work with at all. I would do some research over at the Beretta forum.

Beretta Rifle Forum

Ammo is an issue in any firearm, especially for one that is a blow-back action. That type of firearm is really sensitive to the balance of the action spring, the weight of the bolt, and the power of the round being fired. I shoot 99% reloads (my own) in my CX-4 and have never had an issue. From what I do know about these rifles your problem is not common. But, I believe you said you got it used?

My first suggestion for any issue like this is to try some good, name brand ammo. Then, on your CX-4, there were some issues with ejectors on the early ones. They are super simple to replace and easy to get from Brownell's.

Look here: Extractor

If you go over to the Beretta Forum you can find all sorts of good info on this, maybe even a picture of what to look for on that extractor. Also, I would consider calling Beretta as they use to send out replacement extractors. That was a few years back however so I can not tell you that they will do this now. But, worth a try!.

So, try known good quality full power ammo. Go look at the Beretta Forum for advice. Check the extractor and replace if needed.

Good luck with your rifle. I enjoy mine.
An Army Veteran and proud of it. Long time NRA member and you should be too!
familyman357
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Posted: 1/16/2012 11:49:33 AM
[Last Edit: 1/16/2012 11:52:58 AM by familyman357]
Disergard. I glossed over the part where you said "The trigger continues to not always reset." So, this was a problem before you swapped to the Sierra Papa trigger, correct?
tda1337
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Posted: 1/16/2012 1:00:40 PM
ammo : i now only use USAammo (tho i havent tried since their factory switch) or Speer lawman for target. both loads have had 0 FTE for me
extractor: ill try to replace that, maybe that will help, but it seemed load dependent.

forever, ill check beretta forums again, but found more info here pertaining to my trigger issue here lol

familyman
as far as continues, yes you are correct, the trigger issues were prior to the trigger switch. I thought installing the SP switch would solve some of the issues. it made it a crisp pull, but sometimes doesnt reset as well
in this case I cannot rely on my CX4 for anything but target.
the prior ar15 thread i mentioned stated it was the "transfer bar"
not sure if a new trigger bar would help, or if i need to change a spring
there is no "transfer bar" in the CX4 diagrams, but a trigger bar
forever4
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Posted: 1/16/2012 3:26:27 PM
[Last Edit: 1/16/2012 3:27:31 PM by forever4]
OK, I now have a better idea of what you are say, when you fire it the trigger doesn't reset. Now, you said it did this BEFORE you did the SP trigger upgrade, if I have that correct.

I wish I had this thing in front of me, I think I have some ideas of what MIGHT cause it. Its far easier to describe when the parts are in your hands. Now, seeing as you got it used this problem may have come with the rifle. There is not a lot of parts involved with most triggers and this one is no different. My question here is whether the previous owner might have modified something a bit "too much" and pushed this thing over the line one some minute adjustment.

There use to be a website that had a good picture thread on taking this group apart. If I had more time I could do a new one, but other projects are higher on the list. For now what I can tell you is that the sear catches the hammer when it comes back after a round is fired. This sear holds the hammer back until you let go the trigger. Now, if you pull the "upper" off the rifle you can manually operate the trigger and observe the parts doing their job. BUT be careful. You need to control the movement of the hammer by restricting it with your thumb.

First, take a look at the trigger transfer bar that goes from the trigger back to the center of the hammer. It has to be in the proper position during various times to make the sear work right and to allow the hammer to function. Notice that the rear of that bar, just before it bends over to enter the hammer it has a "bump" on the top. This bump has to align with a cut out in the bolt to allow this trigger bar to rise up. There is a spring that should be pushing upward on this bar to try to maintain it in the upward position. This is a "Closed Bolt" safety to allow the trigger to only work when the bolt is fully in battery.

Next, as the bolt travels reward the bottom of the bolt SHOULD push downward on this bump enough to allow the trigger transfer bar to engage the sear that holds the hammer back until you release the trigger. (if that bump was not tall enough that might prevent the sear from latching). Also, hidden inside that hammer is a little bar that works with the transfer to lock the hammer back. It has to be free to move also. Study how the hammer locks and you can see just how this little guy does his job. You can operate all of this while the lower is off the rifle and see if these pieces work the way they should. Its not rocket science, once you see what is suppose to happen you just have to figure out which piece is worn, bent, or not adjusted right. You may have to take the hammer out and look inside to see if the parts are all OK, not rounded off or anything. There again, if someone has tried to polish these doing a DIY trigger job they might have gotten carried away.

IF, and that is a big IF, the ammo is powerful enough to send the bolt fully rearward then the problem is likely in these small parts. Again, not rocket science, just a few metal bars interacting. If I recall the SP trigger takes some careful adjusting. But, if you are confident that you have followed all their instructions then the rest you should be able to work through.

Good luck with this. Again, just sit and study it and watch each and ever part until you can understand what each one does. Then it should be clear which piece is to blame. Of course, if you had a working one right next to you it might go easier as you have something to compare it to.

Now, if you need any more info that that you can send me the lower with a blank check and I can fix it for you.... just kidding.....

An Army Veteran and proud of it. Long time NRA member and you should be too!
familyman357
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Posted: 1/16/2012 5:17:52 PM
[Last Edit: 1/16/2012 5:19:46 PM by familyman357]
Originally Posted By forever4:
There use to be a website that had a good picture thread on taking this group apart.


You're probably thinking of Tactical Excellence. The text is still there, but the pictures are dead.
Fortunately, Sierra Papa has the Tactical Excellence text AND photos on his website:

Start here...

http://www.sierrapapacx4.com/CX4_Working_on1.htm

and then go to here (also a link from the above page)

http://www.sierrapapacx4.com/CX4_strip/cx4strip1.htm
forever4
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Posted: 1/16/2012 9:59:56 PM
Originally Posted By familyman357:
Originally Posted By forever4:
There use to be a website that had a good picture thread on taking this group apart.


You're probably thinking of Tactical Excellence. The text is still there, but the pictures are dead.
Fortunately, Sierra Papa has the Tactical Excellence text AND photos on his website:

Start here...

http://www.sierrapapacx4.com/CX4_Working_on1.htm

and then go to here (also a link from the above page)

http://www.sierrapapacx4.com/CX4_strip/cx4strip1.htm


Thanks for posting that. I was in a hurry today and forgot to go look for that. We had a meeting to attend this evening.

In the first picture you can see where the part lock together. This is where the trigger transfer bar and the sear come together. Its in this area where I question the operation of the trigger assembly. These things have to interact properly for the sear to lock back the hammer when the bolt moves rearward while you still have the trigger depressed from the last round. If the sear does not catch the hammer it will fall before you have a chance to let off the trigger. Things happen fast when a firearm goes BANG.

An Army Veteran and proud of it. Long time NRA member and you should be too!
tda1337
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Posted: 1/17/2012 12:06:01 PM
thanks ill play with the trigger with the upper off and watch it.

the main problem seems to be with the trigger bar, as the hammer IS cocked back even with the trigger not reset. so ill double check that action with the advice given.
im off from work tomorrow so ill let you guys know

I also have the full disassembled how-to archived for myself when i saw all those pictures missing the first time.
good idea to make myself PDF files sometimes. I used it to install the SP trigger assembly.


good thing its not my self defense weapon
for that my saiga .410 will be here next friday. and ill always rely on my m9 or sig 1911tacpak


and of course, my SHTF stag model 8! lol
forever4
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Posted: 1/17/2012 4:14:43 PM
Let us know what happens. My CX-4 is as dependable as any firearm I have ever owned, your's should be too. Probably something small is off. That is how it goes with weird problems. You look, look and then finally something like a little spring that you wouldn't think matters turns out to be the key to it all.
An Army Veteran and proud of it. Long time NRA member and you should be too!
tda1337
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Posted: 1/20/2012 6:44:11 PM
bad news, and the worst i feared.....
I will use this diagram to give you guys an idea of what happened... and ideas to fix
http://www.brownells.com/.aspx/pid=0/sid=873/schematicsdetail/CX4

part # 54 fell out of the gun while cleaning... not a good sign.
it goes on part #33 (on the back side as you can see in the diagram)
Bad news is part #33 is plastic. even worse, the little tab that holds part 54 in (you'll notice the two side notches, and a small PLASTIC tab on top) is also plastic

needless to say part #33 is of uber-faulty design. its the cheapest plastic ive ever seen. cheaper than an ebay cell phone cover.
any ideas how to fix the tab?