The trigger adjustment screw

If we install the hammer/trigger/spring upgrade parts into your trigger housing (or even if you do it yourself) it may be necessary to repeat the adjustment of the trigger adjusting screw after your CX4 has been in use for a short time. Because of the way they are made all CX4 trigger housings vary a little in size, we adjust the trigger in one of our test guns so your gun may be slightly different and the screw may need to be adjusted to match your gun. This is a simple adjustment but go slowly, adjusting the trigger adjustment screw a little at a time, until you find the correct position. The good news is that once the adjustment is made correctly it should not need to be repeated for many rounds fired.

First, the symptoms. The most likely symptom of incorrect trigger screw adjustment will be that the gun fires correctly for the first round after chambering a round using the cocking lever but it subsequently fails to fire in semi-auto. The trigger will be free to move through it's full range of travel but there is no hammer release. If the case is a slight mis-adjustment the failure to fire may be quite infrequent but the feeling will be the same, full and free trigger movement but no hammer release. In a mild case it may be that a pushing the trigger forward will allow the gun to be fired after an initial failure.

IF THIS TYPE OF FTF HAPPENS BE CAREFUL. THERE IS NOW A LIVE ROUND IN THE CHAMBER AND THE GUN MUST BE UNLOADED AND MADE SAFE BEFORE YOU DO ANYTHING ELSE.

Solution.

Find the special Allen wrench we supplied, it will probably be in the small plastic bag containing your original parts. Remove the upper of the gun from the lower. Find the adjustment screw (see photo in post below). Engage the wrench into the screw (I know, this is fiddly but this is the only place we could put the screw). UNSCREW the screw about 1/8th. of a turn (because of the tight space this is about the maximum you will be able to unscrew the screw in any case). Assemble the gun and perform a live fire test on the range since a dry fire test does not give accurate results.

Results.

If, after you have made the adjustment, your gun works properly the problem is solved. If the problem is not solved try another small adjustment. If the problem is still not solved then please 'phone us since there may be other factors involved. The adjustment is pretty critical. If the screw is screwed too far in then the trigger will not reset and the gun will not fire. If the screw is adjusted too far out then the gun may be difficult to cock (after adjustment you should still be able to cock the hammer with your thumb with the upper removed).

Back story.

As with all semi-automatic firearms there must be a way to disconnect the trigger of the CX4 from the rest of the firing mechanism to prevent the gun going fully auto. You probably would not be surprised that this mechanism is called - the "disconnector". This is how the disconnector works on the CX4.

If you look underneath the trigger housing you will see that the rear end of the forward trigger bar (the one with the 90 degree bends around the magazine in it) has a hook on it. This hook connects with a projection on the forward end of what I call the rear trigger bar. With the gun in a ready to fire state the hook and projection are engaged with each other. As you pull the trigger the forward trigger bar pulls the rear trigger bar (and the hammer pivot pin) forward. The hammer pivot pin, of course, pulls the hammer forward and the hammer disengages from the sear allowing the hammer to rotate upwards and strike the firing pin. After the cartridge ignites the bolt is pushed rearward. Up until this point a projection on the top edge of the forward trigger bar had been resting in a cutaway on the lower right-hand surface of the bolt. As the bolt moves to the rear the projection on the forward trigger bar is forced down by the bolt which forces the hook at the end of the forward trigger bar to disconnect from the projection on the forward end of the rear trigger bar and the trigger is DISCONNECTED from the hammer mechanism. Eventually the bolt returns to the forward position loading a new cartridge and allowing the projection on the top of the forward trigger bar to enter the cutaway in the bottom of the bolt, then, when you allow the trigger to go forward again the hook and the projection reconnect and you are ready for the next shot.

Quite simply, what is happening when the trigger adjusting screw is too tight is that the hook on the forward trigger bar is not reconnecting with the projection on the rear trigger bar. Unscrewing the screw a little allows for correct re-engagement.

 

 

If you feel you must fit the hammer/trigger/spring kit yourself.

As you know we will fit the hammer/trigger/spring kit into your trigger housing and return the old parts to you at no charge. Here are a few tips if you wish to do the job yourself. The mechanical job of fitting the parts is not too difficult but making adjustments that may be required to the original Beretta parts and getting the final adjustments correct is a little more tricky.

Trigger Parts

If you receive the kit as individual parts in plastic bags then the trigger adjustment screw will not be installed in the trigger. This is because the screw is coated with blue Loctite compound which hardens after the screw has been in position for about 12 hours. If we shipped the trigger with the screw in place the Loctite would harden before you received the parts.

There are two threaded holes in the aluminum trigger, one is for the screw used to adjust the trigger "pre-travel" and this screw is used with both the plastic and aluminum trigger housings, the other screw is used to adjust the trigger "overtravel" and this screw is used only with our aluminum trigger housing.

The "pre-travel" adjustment screw position is shown below.

Using the small Allen wrench supplied with the parts kit screw the trigger adjustment screw into position so that the tip of the screw is flush with the rear face of the trigger (in the cavity at the rear of the trigger). Assemble the trigger/trigger spring/hammer linkage/trigger pivot pin group into the trigger housing. Hammer Parts Replacing the hammer parts should be fairly straight forward. Initial Adjustments. Now the job gets a little more tricky. We need to make initial adjustments to the trigger adjustment screw before we continue. This is a critical adjustment. This is probably how the catch at the rear of the trigger housing will look at this point.

Using the small Allen wrench supplied with the parts kit screw the trigger adjustment screw into position so that the tip of the screw is flush with the rear face of the trigger (in the cavity at the rear of the trigger). Assemble the trigger/trigger spring/hammer linkage/trigger pivot pin group into the trigger housing.

Hammer Parts

Replacing the hammer parts should be fairly straight forward.

Initial Adjustments.

Now the job gets a little more tricky. We need to make initial adjustments to the trigger adjustment screw before we continue. This is a critical adjustment.

This is probably how the catch at the rear of the trigger housing will look at this point.

Note that the little hook is in the fully engaged position. Now, screw in the trigger adjustment screw until it starts to contact the trigger housing body. This will take a little movement initially since the screw was deliberately pre-set to provide clearance between the screw and the housing to ease assembly (see above). As the screw contacts the trigger housing body the little hook will start to move down in its slot. Stop screw adjustment when the top of the hook is level with the bottom of the metal plate, as below.

Note that the little hook is in the fully engaged position. Now, screw in the trigger adjustment screw until it starts to contact the trigger housing body. This will take a little movement initially since the screw was deliberately pre-set to provide clearance between the screw and the housing to ease assembly (see above). As the screw contacts the trigger housing body the little hook will start to move down in its slot. Stop screw adjustment when the top of the hook is level with the bottom of the metal plate, as below.

This will be the starting adjustment position for the trigger adjustment screw. At this point you should be able to push the hammer down with your thumb and cock the action and you should be able to pull the trigger and release the hammer. If you cannot cock the hammer easily then screw the trigger adjusting screw in SLOWLY until you can just do this. If you screw the trigger adjusting screw in too far the trigger will not reset correctly in live fire use. Next, fit the sear clip. Because of the extra thickness of the metal clip you will probably now not be able to cock the hammer with your thumb. If this is the case screw the trigger adjustment screw in a little further until you can do this. You now have the trigger adjusted for range testing. Assemble the gun and check trigger operation. There will be trouble-shooting tips in the next post.

This will be the starting adjustment position for the trigger adjustment screw. At this point you should be able to push the hammer down with your thumb and cock the action and you should be able to pull the trigger and release the hammer. If you cannot cock the hammer easily then screw the trigger adjusting screw in SLOWLY until you can just do this. If you screw the trigger adjusting screw in too far the trigger will not reset correctly in live fire use. Next, fit the sear clip. Because of the extra thickness of the metal clip you will probably now not be able to cock the hammer with your thumb. If this is the case screw the trigger adjustment screw in a little further until you can do this. You now have the trigger adjusted for range testing. Assemble the gun and check trigger operation.

There will be trouble-shooting tips in the next post.

Beretta Upgrades the Trigger Housing.

The finish quality on the trigger housings has improved recently with the most notable feature being a redesign of the safety catch at the extreme rear of the housing. I do not know when the redesign took place but we have seen a large proportion of the new design housings recently.

This is the old design showing a failed unit. There should be a little metal plate in the "pocket" at the rear of the housing - this has fallen out. The way the plate is normally secured is by a small plastic clip at the top front of the pocket. This has broken off in the photo and the metal plate has therefore popped free. This was a poor design and failed frequently.

This is the new design.  

This is the new design.

 

The metal plate is now larger and it is molded permanently into the plastic of the housing, a much better design. The improvement was made by modifying the original molds because you can still see the original plastic clip from the old design molded into the new unit at the top center of the plate. This actually causes us a problem. Our metal sear clip is matched to the old design. It can be modified to fit the new design but this takes some skill and some special jigs. We will be having new sear clips produced to fit the new design but until they are available we will need to re-bend the original parts. SO, unless you really want to do the work yourself please send us your complete trigger housing so that we can do the work for you.

The metal plate is now larger and it is molded permanently into the plastic of the housing, a much better design. The improvement was made by modifying the original molds because you can still see the original plastic clip from the old design molded into the new unit at the top center of the plate.

This actually causes us a problem. Our metal sear clip is matched to the old design. It can be modified to fit the new design but this takes some skill and some special jigs. We will be having new sear clips produced to fit the new design but until they are available we will need to re-bend the original parts. SO, unless you really want to do the work yourself please send us your complete trigger housing so that we can do the work for you.

How to get time off from work.

Now, you guys in other places may just look on this as light snow but we are not used to this sort of thing in Oregon - not over one night. The bricks are two inches thick so we were looking at 10 to 12 inches of snow. But the snow does have its compensations.  

Now, you guys in other places may just look on this as light snow but we are not used to this sort of thing in Oregon - not over one night. The bricks are two inches thick so we were looking at 10 to 12 inches of snow.

But the snow does have its compensations.

 

We were trapped in the house for seven days because we could not get down our drive to the main road. Then the day the snow cleared USPS delivered 20 packages of trigger housings so it was "back to work".

We were trapped in the house for seven days because we could not get down our drive to the main road. Then the day the snow cleared USPS delivered 20 packages of trigger housings so it was "back to work".

MORE MISCELLANEOUS TIPS AND COMMENTS.

GUIDE ROD UPGRADE

The guide rod upgrade makes a significant and critical contribution to the reliability of your CX4. A broken guide rod means no operation, nothing, not even a single shot rifle.

So, what do we need to upgrade your guide rod? Simply your original guide rod assembly. Actually all we REALLY need is the guide rod spring itself but unless you enjoy fighting strong oily springs and awkward fittings it is easier just to send us the whole assembly. Remove the original guide rod group by first removing the thin metal, horseshoe shaped, clip on top of the bolt then lift out the guide rod complete with buffer. We do not need any other part of the actual bolt assembly.

Replacement of the upgraded guide rod should be fairly simple if you make a note or take a photo of what you are doing when you initially remove the original guide rod. If a problem does occur on reassembly it is usually because of mixing up the extractor and ejection parts.

So, simply send us your original guide rod assembly and we will return an upgraded item complete with new style buffer and your original parts in a plastic baggy.

When you have your upgraded guide rod you should never need to disassemble the unit again (although we do supply a suitable Allen wrench) . You can clean the assembly by using a spray cleaner or by brushing with solvent and then re-lubricate by dripping oil through the spring coils at a couple of points along the length of the rod.

The buffer on the upgraded guide is a push fit only. It is trapped in position in the last 1/4 inch of movement as you push the upper and lower together and the buffer cannot possible come free during use of the gun. And, Yes, we made the buffer correctly. It does not need to have any more holes drilled through it to make it look like the factory part. (Guilty parties please note. )

It is still a good idea to cock the hammer of your CX4 when you remove or replace the upper and the lower. Our steel guide rod will not be damaged if you forget to cock the hammer, the buffer will simply pull off from the guide rod, but the oily and dirty buffer will then fall from the gun, land on your wife's new white carpet leaving an oily mark and then you will be in more trouble than the BATFE could cause you!

 

Miscellaneous Tips and Comments.

The following are a few comments which should allow us to make life easier for you during these kit installations. Some comments will cover the actual hardware installation and some are explanations of how the CX4 works which may help you to troubleshoot problems,

So, here goes, in no special order.

Parts for Trigger Upgrade.

If you send a trigger assembly to us for upgrade include the following parts.

a. The trigger housing including the original trigger and hammer components.

b. The bolt stop lever, part number 39 in the Beretta parts diagram for the CX4.

Link : https://www.brownells.com/schematics/Beretta-/CX4-sid873.aspx

(This is the original Brownells parts diagram, thanks to Brownells.)

The reason I would like to have the bolt stop is because it can be very fiddly to reinstall the bolt stop without accidentally distorting the trigger spring (part 35, which can cause all sorts of problems). Send the bolt stop and I will re-install it for you. (See comment under "Safety Button" below).

We do not need the safety button or the bolt stop release lever.

Safety Button

As you have probably worked out by now the trigger housing is secured into the CX4 lower by the safety button. To stop the safety button falling out during normal use this part is held in place by a triangular projection on the lower edge of the bolt stop lever. To remove the safety button you need to lift the bolt stop lever just enough for the safety button to be pushed free (this can be done in either direction). YOU DO NOT NEED TO REMOVE THE BOLT STOP LEVER COMPLETELY FROM THE TRIGGER HOUSING IN ORDER TO REMOVE THE SAFETY BUTTON. Simply lift the bolt stop lever sufficiently to allow the safety button to be pushed out of the lower and the trigger housing.

Of course, to lift up the bolt stop lever you will need to free its rear end from the bolt stop release lever first. This operation is covered in our trigger housing disassembly video.

Now, when you replace the safety button into your upgraded trigger assembly MAKE SURE IT IS ORIENTED CORRECTLY. I have had more than one phone call telling me that the gun would not fire because the trigger could not be pulled. It usually does not take much time to find out why. Remember, the safety button can be reversed for right or left hand shooters but it can also be fitted upside down!

 

 

SHOP CLOSED UNTIL MONDAY

Due to usual winter weather in the Northwest and Portland Metro area over the past several days, our shop will be temporarily closed until Monday, January 16, 2017. We are experiencing power outages and dangerous road conditions at this time. Conditions are expected to change as temperatures rise over the next few days allowing us to resume business as usual. We appreciate your understanding if we are unable to take your calls or respond to emails right away. We will respond to all inquires at our earliest opportunity. Thank you!

A tip to make your life simpler.

Please, when you send us parts include the following items.

If you need a trigger assembly upgrade please include the bolt stop lever (Part #39). We will install this part so you do not have to fight the tricky spring that holds it in place.

If you need our steel guide rod kit send us the complete guide rod assembly as removed from the gun. We do not need the bolt. We will remove the spring from the original rod, transfer the spring to the new steel guide rod and return the original parts.