Help with fail to fire on M4

[huskAR]

I'm a new M4 user.  I have lots of experience shooting inertia Benellis but the M4 is causing me some problems.

I start with a shell in the chamber.  I load the mag tube, I press the cartridge drop lever and a round pops into place.  I take aim and pull the trigger, the fire round fires as expected.

The gun cycles and loads the next round.  The second shot goes click (no bang). 

When the gun goes click, the trigger actuates and the hammer definitely falls.  But the gun does not fire. 

There is no dimple on the primer, it is not a soft strike. 

If I pull the bolt back and lock to the rear and then reload , the first round always fires.  But the second shot always fails.

I have repeated this sequence a dozen times with different shells just to make sure that its not the ammo.  I am firing 00 Buck at 1450 ft/sec so these are not light loads.

Am I making a rookie mistake or is there a malfunction somewhere?

huskAR

[StrangerDanger]

You don't need to press the shell drop lever. The shotgun will load from the magazine tube on its own.

[Ben elLes]

Yeah try not hitting the button unless your loading on an empty chamber

[RxArms]

This is all true (about the shell drop lever), but the gun should still fire, even with a ghost load it fires.

first trouble shoot would be to just load the mag tube with one in the chamber and see if it cycles normally (no ghost load no shell drop lever)

Edited October 6, 2022 by RxArms

[huskAR]

I did not ghost load during any of my test fires. 

 

[D'zaster]

So, it fires the first round, chambers the second round but does not go bang? Is the magazine cap screwed on all the way (bbl fully seated)? If so, I'd suggest field stripping it to inspect the bolt assy.

[huskAR]

Yes, Magazine cap is fully on.  It function checks ok, but I will take it apart and look at it.  .  The weirdest thing about the malfunction is the bolt goes to the rear far enough to extract the spent shell and chamber the new shell.  The hammer falls when the trigger is pulled on the second shot but its like the firing pin doesnt get touched.

 

[Don Randall]

How many rounds have you fired with this M4? 

Regarding the rounds that "fired", does the primer look like a normal firing pin strike? If the strike looks normal, then your problem most likely is with the bolt assembly. 

Remove bolt assembly, dismantle, clean and lubricate per the M4 operator's manual. Pay close attention to how the firing pin, firing pin spring, firing pin retainer pin, and bolt cam pin are assembled. Keep in mind that the firing pin assembly is an inertia system that also functions as a passive safety mechanism (i.e., drop safety).

Look for any obvious firing pin assembly issues (e.g., bent spring) and does it all reassemble without forcing any component in place (i.e., an alignment issue). 

Look closely at the cam pin grove for an excessive wear or impediments to movement (i.e., smooth operation). This is important because the axial movement of the bolt and the cam pin controls bolt head rotation of approximately 20 degrees to lock/unlock the bolt with the barrel. There is a designed gap between the bolt carrier and the bolt head serving as a passive safety mechanism; if that bolt head is not fully locked with the barrel the firing pin head may fall short of hitting the shell primer. 

The cam pin just floats back and forth during the cycling; that is, the action recoil spring powers the bolt closure and the ARGO pistons power the bolt to open. You stated "the second shot always fails"; so that would point to a possible action recoil issue. Inspect the bolt carrier link bar and link pin for any abnormalities (binding, wear, etc.).

After reassembly and inspections are all good, then perform function checks per M4 manual, manually cycle and dry fire several times and listen for consistent movement of components, and then load "dummy rounds" and repeat.  Then go to the range and try again. 

During your inspections, if you found something that looks odd, take a picture and post. Of course, if it looks odd, your best bet is to take it to a gunsmith. 

[huskAR]

Don, I have fired about 20 rounds out of this shotgun.  I am the second owner of the gun.  The original owner unfortunately is deceased so I can't ask him for any history.  I did talk to the son of the owner who said the gun was lightly used and that it functioned in the past with no problems.

I should probably mention that I replaced a couple of the trigger pieces as well as the magazine tube with parts from Freedom Fighter Tactical to make the gun 922r complaint. 

I did not pick up the old shells that I fired to inspect the pipers but will do so when I go to the range this Wednesday to resume test firing.

I followed your recommendation to disassemble and inspect all parts.  All parts in the bolt assembly look perfect.  I posted pictures in the thread for your reference.  You will notice very little wear on any of the parts so far.

I will report back later this week with additional findings from more live fire.

If the pictures spark any thoughts, please let me know.

[huskAR]

The parts I installed on the M4 are the from the Freedom Fighter Tactical website.  The parts seem like they are well made.  The picture from their website is below.  The parts description is:  All four variants contain three FFT 922(r) Complaint trigger parts, including the premium hammer, premium trigger, premium disconnector, and the FFT / Wolff Gunsprings Trigger Kit Replacement Springs.  

I'm not a gunsmith, but i feel like the assembly was easy and I don't see anything obviously wrong with the trigger assembly.  However, since I stated that the second shot fails, it does make me wonder if the hammer isn't striking the firing pin properly on the second shot.

[Don Randall]

15 hours ago, huskAR said:

The parts I installed on the M4 are the from the Freedom Fighter Tactical website.  The parts seem like they are well made.  The picture from their website is below.  The parts description is:  All four variants contain three FFT 922(r) Complaint trigger parts, including the premium hammer, premium trigger, premium disconnector, and the FFT / Wolff Gunsprings Trigger Kit Replacement Springs.  

I'm not a gunsmith, but i feel like the assembly was easy and I don't see anything obviously wrong with the trigger assembly.  However, since I stated that the second shot fails, it does make me wonder if the hammer isn't striking the firing pin properly on the second shot.

I don't see anything from your pictures that look abnormal. The component wear interfaces indicate a relative low firing rate. 

In regard to the FFT trigger assembly replacement for 922r compliance, I must complement you on the endeavor. The most complex part of any Benelli shotgun is the trigger assembly. I watched a FFT 922r trigger upgrade below. If you still are having the same issue after your next range event, I would reinstall the Benelli M4 OEM trigger components and retry. If still having issue, it is time to see the gunsmith. 

 

[sas-M2T]

On 10/6/2022 at 1:01 PM, huskAR said:

.

 

Edited October 10, 2022 by sas-M2T
question already asked.

[NoTycoon]

Early on, my M4 had the same issue. I determined that the bolt did not come back far enough to fully cock the trigger.  I put in a lighter recoil spring to solve the problem. As I recall, in later years, I went back to the factory spring after the gun was better broken in. I have had my M4 for about 15 yrs.  My only current issue is needing to use hotter loads in cold weather (Win XX low brass #8). I can run cheaper loads (Win white box, Rem Target, Estate) only in hot weather.

[huskAR]

PROBLEM IDENTIFIED

The install video posted above by Don Randall has the problem articulated at timestamp 21:30.  There is a problem with the Disconnector being slightly out of tolerance and the trigger catches on the reset and prevents the sear and hammer from engaging properly. 

 

[huskAR]

This video shows exactly what is going wrong on my specific trigger pack.

I hope this helps everyone understand the problem.  The fix is still in the works.

https://rumble.com/v1ntssa-benelli-m4-trigger-pack.html

 

[huskAR]

I need to correct my original description of the problem. 

I start with a shell in the chamber.  I load the mag tube, I press the cartridge drop lever and a round pops into place.  I take aim and pull the trigger, the fire round fires as expected.

The gun cycles and loads the next round.  The second shot goes click (no bang).  This part needs to be amended.  The trigger did move, but the hammer did NOT release and hit the firing pin. 

 

[StreetSweeper56]

I've been following your thread, you replaced the OEM trigger to make it 922r compliant. Was there something else replaced that took it out of compliance? Maybe I missed it; I have 2 M4's and have never felt the need to replace the triggers as they work fine.

[huskAR]

StreetSweeper,

I replaced the original 5 shot magazine tube with a 7 shot magazine (also an aftermarket product from Freedom Fighter Tactical).  That change required me to replace 3 parts in the gun to US made parts, so I chose the 3 trigger parts figuring that would be the easiest.  The other parts that could be replaced are listed in this article:

https://freedomfightertactical.com/pages/922r-faq

With all that said, I would NOT do this again.  I have the titanium coat on the Benelli and went with the FFT magazine tube so the color would match.   (I didnt want a black magazine tube on a silver gun).  Between the trigger kit, the magazine and stiffer magazine spring, and the Mesa Tactical shell carrier, I spent $800.  The gun is beautiful and the quality of the original gun and the shell carrier ensures it will survive hard use in a war zone.  With that being said I'm $2600 into this gun and had many teething pains to get it to work properly.

If I had this to do all over again I would buy two Beretta 1301s. 

[huskAR]

OHHH. and I forgot to mention the most important disappointment in installing the 7 shot magazine tube.

It only holds 6 shots. 

After all the hassle, you come to find out that the 7th shell wont fit.  You are about 1/4" short.

After much research I found a video where the manufacturer suggests that you shop around for an ammo brand that has slighter shorter shells so you can fit the 7th shell.  So far I haven't found one.

 

[StrangerDanger]

I've had to fit many of those FFT trigger kits in recent years for hanging on the disconnector. I found the best option was to use a small file and to remove material from the hammer sear until the trigger disconnects properly. I like to do the work when the hammer is installed so I can quickly check my work.

If you haven't done so already, set the spring retainer in the end of the magazine cap so it sticks out past the end of the magazine tube. As you install the magazine cap, you'll feel it press the retainer into the depth it needs. Setting the retainer in too deep can limit the room you have for shells. There are a lot of 2 3/4 shells that don't conform to the size standards. Stacking up 7 of them ends being slightly longer and prevents the 7th round from fitting.

[StreetSweeper56]

2 hours ago, huskAR said:

OHHH. and I forgot to mention the most important disappointment in installing the 7 shot magazine tube.

It only holds 6 shots. 

After all the hassle, you come to find out that the 7th shell wont fit.  You are about 1/4" short.

After much research I found a video where the manufacturer suggests that you shop around for an ammo brand that has slighter shorter shells so you can fit the 7th shell.  So far I haven't found one.

 

There was a thread on this last year, Fetter will fit 7 but they're from Russia and I have not seen any for sale in quite a while. Fortunately, for me, I bought a boatload at the time. Even with 6 in the tube, 1 ghost load, 1 chambered and 5-7 on a side saddle that's a pretty hefty load out on board. I suggest a "match saver" as well. 

https://forums.benelliusa.com/topic/24945-fetter-00-buck/#comment-164436

 

Edited October 13, 2022 by StreetSweeper56

[huskAR]

StrangerDanger I have a question about your instructions

Are you recommending removing material from the disconnector (marked in red) or from the back spur on the hammer (marked in yellow)?

[StrangerDanger]

The yellow marked area, that way you aren't messing with the chrome plated finish. The only part of the hammer that you'll be kissing with the file is the tip marked by the top of your yellow line. You only end up having to remove a few thousandths of an inch. Its hard to see inside the polymer trigger frames, but you can see the hammer hook hanging on the front edge of the disconnector seer when the trigger is not being pressed. When the trigger pack is working correctly, the hammer hook will hang on the disconnector until you release the trigger. Once you release, you'll hear a click as the hammer slips from the disconnector and engages the trigger sear. From this point, the hammer will drop if the trigger is pressed again (when the safety is off.)

So I decock the hammer, and have the trigger guard locked in a padded vice so my hands are free. I then run a small file along the mentioned area 10-15 times. Wipe it clean, and test kit again. You'll find you'll get it to a spot where it just barely slips by. I'd recommend removing a little more material so it doesn't hang during the recoil impulse. You don't have to press hard on the file. You want the surface to be as smooth and even as possible across the hammer sear engagement surface.

Then once you have it where its functioning, I'd use a good grease on the sear contacts. I like the Brian Enos' Slide Glide standard weight, but any good grease will do fine.

[huskAR]

FIXED!!

https://rumble.com/v1nv98c-benelli-m4-freedom-trigger-post-filing.html

Thank you everyone especially StrangerDanger, Don Randall and Streetsweeper for the hints and dialog.  I really appreciate it!

[StrangerDanger]

Good job! Sorry I didn't diagnose the issue from the first message right. I didn't know you had added those trigger pack parts.