Cleeford...where are you with the M4 Disconnector?

[ME163]

I have been out of the net for awhile...but i'm back. For my stock to be in compliance i need 4 USA parts and i am looking forward to the Made in USA Kip Carrier Comp Disconnector, thank you very much.

ME163 Out:)

[BigHat]

Have you purchased the Geissele hammer yet? You can get it directly from them if you wish. Right now the demand for ADDITIONAL compliant parts is pretty low. You get a US Tube, Follower, Hammer and Forearm/Handguard you're all set, even with the collapsible stock. I wouldn't mess with the disconnector. If I do, it will be because Geissele makes an entire trigger assembly. But a precision trigger isn't essential in a shotgun so I doubt the demand will be sufficient for them to even make it. I'd be careful when buying fire control parts from people that don't do it as a core competency. Aside from Benelli, the only one making the hammer is Geissele.

Edited November 4, 2011 by BigHat

[ME163]

BigHat

Yes. i have purchased the Geissele hammer. I hope Kip comes up with the disconnector...soon. Last i heard from Geissele, their TG assembly for the M4 has a low...priority...Thanks for the update.

ME163 Out

[tucker301]

[StrangerDanger]

I'm still interested in this. Kip had mentioned in the past that he had a modified geometry for the disconnector to reduce the hammer drop issue. As soon as the shell elevator drops, the hammer will fall if the trigger is pulled while the bolt is still cycling forward.

 

You end up with a hammer down on a live round in the chamber. Even with high brass loads, I can beat cyclic action and induce this failure.

[TKTM]

Doesn't the ATF shotgun study reduce the number of needed 922r parts by 1 ?, ie the pistolgrip is now allowed for import

[benelliwerkes]

[ATTACH=CONFIG]1086[/ATTACH][ATTACH=CONFIG]1087[/ATTACH]

I'm still interested in this. Kip had mentioned in the past that he had a modified geometry for the disconnector to reduce the hammer drop issue. As soon as the shell elevator drops, the hammer will fall if the trigger is pulled while the bolt is still cycling forward.

 

You end up with a hammer down on a live round in the chamber. Even with high brass loads, I can beat cyclic action and induce this failure.

 

Why is blame singly assigned to the disconnector ? The disconnector is not solely responsible for securing the hammer in the cocked or almost-cocked positions, the trigger sear notch and the disconnector sear notch both perform that function on opposite sides of the hammer surface. The disconnector is only serving to retain the hammer in the cocked position when the trigger remains pulled during the action cycling. When the trigger is released the hammer control tasking is handed off from the disconnector to the trigger sear which controls the hammer position.......if the hammer has followed the bolt forward during the action cycling, the hammer notches have have failed their jobs, not the disconnector alone. Either the rapid vibrations of the cycling has interfered with the trigger return / disconnector springs harmonics not keeping up with the velocity of the bolt cycling or a too loose tolerance between the trigger sear / disconnector sear and the two hammer notches - a tolerance mismatch that is exposed during rapid cycling causing the hammer to not be captured by either the disconnector or the trigger and therefore the hammer follows the bolt forward at similar velocity not causing primer ignition.

 

Also, the problem of the hammer not being captured by either the trigger sear or the disconnector sear is a bolt moving forward mechanical timing problem - the forward speed of the bolt is dependent on the expansion of the action recoil spring assembly, and thus independent of the cartridge load which might alter rearward bolt speed in some benelli actions e.g. inertia bolt system. The point being, if the "disconnector" problem is present and can be unmasked by the operator, it should be demonstrable with any cartridge type.

Edited November 10, 2011 by benelliwerkes

[StrangerDanger]

I can re-recreate the situation by manually cycling the shotgun (unloaded of course). Pull the trigger, and drop the hammer. Manually cycle the bolt to the rear, which engages the hammer hook onto the disconnector. Begin cycling the bolt forward slowly. You'll notice that if you pull the trigger at this time, the disconnector will be functioning fully and the hammer will not drop.

 

As soon as the bolt cycles forward enough to drop the shell elevator, if you pull the trigger during this stage and forward, the hammer will drop on the still cycling bolt. The hammer ends up riding the bolt carrier home with a live round in the chamber. Even though the failure is induced, the weapon is safe and there is no risk of the round igniting out of battery since the bolt must fully rotate and seat into the bolt carrier for the firing pin to protrude enough to make contact with the primer. The hammer travels much faster than the bolt cycles, so it can catch up with the cycling carrier easily.

 

I sent my M4 to Benelli in 2008 to see if there was something wrong with the trigger pack. I thought that maybe the hammer was slipping between the disconnector and the trigger hook. They said everything was in spec.

 

I've calculated the shot times to be at roughly .1875 seconds. How fast the weapon cycles depends on a few variables. How stout you're holding the weapon. The dram of the rounds being fired. Climate (cold really slows things down). Mainspring life and cleanliness. Weighted options such as bolt handles (I run a lighter than stock Design Concepts bolt handle). Proper lubrication of the weapon. Some weapon modifications can cause the cyclic rate to slow down, such as a Tacstar shell carrier.

 

Here is a short video of myself inducing this failure on the very last round. Note that the rounds are high brass #6 field loads. Target was a one gallon milk jug at 15 - 20 feet. All rounds on target. Seven rounds of high brass 12 gauge on target in under 1.5 seconds is pretty devastating. A real testament to the Benelli M4.

 

http://www.youtube.com/watch?v=m_haUjtatkk

You can see on the last round, I had a hammer down situation. I tried pulling the trigger again. Then cleared the weapon when I knew it was a dead stick and would need to be manually cycled to be brought back into the game. Had there been more rounds in the magazine tube, I could have shell dropped, and manually charged the weapon and continued.

[BigHat]

Still unsure about the magnitude of this issue, but a very interesting discussion.

[StrangerDanger]

What it comes down to is I have to slow down before taking my follow up shot or I risk boning myself. I buy high dram stuff to practice with these days to simulate buckshot recoil events. Buckshots a little pricey to shoot as much as I like to.

 

I find myself listening to the cyclic action to determine when it is safe to pull the trigger again. We had some moving targets for a while, and sometimes you weren't sure if you really got a solid hit on the target. So you were wanting a follow up shot to make sure it was enough to incapacitate the simulated target.

 

Sweeping between multiple targets usually gave the action enough time to fully cycle before the next target was lined up.

 

The magnitude of the issue is minimal. I've never heard anyone else even mention encountering it. Previously I thought there was something wrong with the weapon, that's why it went to Benelli. It wasn't a complete waste of time, they replaced the barrel with the 11707, ARGO plugs and pistons, gave me new handguards and an entire new bolt carrier group. The odometer on my M4 just rolled over 13,000 rounds, so I've gotten pretty quick with it over the years. Earlier this year I replaced the entire recoil tube assembly along with a new spring and plunger. It has a stout Wolff spring in the magazine tube, so it feeds great. The only thing that is really unfamiliar territory for me is inside the trigger group.

 

It's done it before and after the carriercomp/geisselle hammer install too. I had wondered if it was a worn hammer hook previously, but it isn't the issue at all. It is the fact that the disconnector doesn't disconnect once the shell elevator drops. Anyone can simulate it with their weapon.

 

When I had a GG&G bolt handle, I could hear the difference in how slow the action was cycling just with it installed. I've even considered nickel boron coating parts in the weapon to try to speed up the action speed to act as a bandaid fix to the issue. If I make it cycle faster, the failure rate would be reduced. I was thinking about coating the recoil tube on the inside, the carrier, bolt and hammer.

 

I'd rather not slow down. I like to walk a double tap of 12 gauge up a target, center mass.

 

I use the push pull shotgun technique to control recoil. With my left hand, I'm squeezing the M80 rail, and pushing forward. While my right hand is pulling the weapon firmly into my shoulder. My left arm acts as a shock absorber and minimizes muzzle climb. I aggressively lean in on the weapon during firing. With the Aimpoint T1, it's like cheating anyway. With the weapon firmly seated against my shoulder, and minimal muzzle climb, the dot remains on target within combat accuracy.