Puzzling Benelli M2 issue. ???

[cas]

I've been having some issue with my main match gun.  I started noticing it when I was testing some other unrelated matters, basically doing "bursts" or mag dumps.  Since it was doing it then, I assumed I was "out running" the trigger, because it would be dead, the hammer uncocked. But after a bit of fiddling and more rounds,  I realized that wasn't it at all, because it will sometimes do it when I fire a single shot. The odd thing (to me) is when it happens, I end up with a shell on the carrier.  It's ghost loading itself.  

 

I end up with a live shell in the chamber, a shell on the carrier, shells in the tube... and an uncocked hammer. 

 

I know it's a shell latch issue because it does it with other trigger groups in the gun as well.

I've had latch issues in that past,  modifying them just a touch too much, or enough so that they don't last anyway.

But what I don't understand is why the hammer wouldn't be cocked? 

For a shell to eject and live one to chamber, they bolt obviously travels far enough rearward to cock the hammer. 

If it were a sear engagement issue / hammer follow, it would be isolated to the one trigger group, but it's not.

 

Anyone seen this behavior before? 

Edited February 9, 2020 by cas

[kurtm]

First off any time the hammer spring cap reaches its highest point, it pushes up on the shell release tab and this causes a shell to be released from the mag tube. If you have ammunioin in the tube and the hammer falls/follows and fails to ignite the chambered round for any reason it is going to release a shell onto the carrier, so you are going to have a live round in the chamber and a live round on the lifter, no and if or but.

Several things can cause this to happen, bolt bounce, recoil spring guide buffer backing out or fallen out. Crack in the back of the shell cut off lever. Cut off lever spring weak or broken, and bolt release button causing drag/bind, ie. Arendondo type.

[cas]

Thanks, that makes sense....   ("any time the hammer spring cap reaches its highest point..")

 

I'm a bit confused by what you mean when you say " recoil spring guide buffer backing out or fallen out"

 

I will re-srping  (because it's probably time anyway) and take a close look at the shell catch. Maybe swap one from another gun to try.

 

The un-cocked hammer has me scratching my head. If it were just the one trigger group I'd figure sear engament issues. But I have the same issue with the trigger group out of one of my other guns.  The hammer is left un-cocked,  you can see it. This isn't the classic "Benelli click" of an un-cammed bolt head.

 

I can tell the gun has malfunctioned before I attempt to fire it by the extra/delayed sound and feel of the extra shell coming back onto the carrier.

Edited February 10, 2020 by cas

[kurtm]

Have you ever changed your recoil spring? If you have the back of the the recoil spring guide, plunger, piece that goes at the front of the spring has a little nub sticking out of the middle of a slotted screw head looking thing. This is a buffer. It consists of a plunger (little nub, very stiff coil spring, and a retainer ring aka slotted screw head looking thing.

Anything else been done to your trigger groups? Taken all the way apart? "custom"  trigger work? Trigger stops? After market trigger group housings? Etc. What all has been done to this gun?

[cas]

I've had the recoil spring out... replaced it once years ago? Maybe? I honestly I don't recall much about it, other than I can remember taking the spring guide plug out. 

 

The guns usual trigger group is an aluminum A&S/Briley aftermarket one. It has a C-Rums welded carrier as it's only other modification.  The other trigger group tried is a bone stock one.  Both do the same thing.  (I was surprised and actually disappointed to find that out) 

[cas]

Okay, it's been a while I guess because I didn't remember the recoil spring plunger... was a plunger. 

 

It's tight and the spring seems to be working. Compresses freely, but firmly. 

[kurtm]

That's good!

[cas]

I dunno. Now  I'm really starting to doubt and question myself the more I think about this. I think I need to let someone else run a few boxes of ammo through it. 

Were my malfunctions on "single shots" really true singles, or was I doing doubles and just don't remember. In trying to see if I've solved the problem, and I making it happen with quick double pulls that are just following the bolt closed? ?  Am I sort of bump firing the gun without realizing it?  (Why I would start doing that after 11-12 years shooting the gun I don't know).

I think this weekend I will shoot, or let someone else shoot a lot of slow singles to see if she does it. 

 

The shell latch looks fine, like it usually does and I'm not getting any stoppages like I would if shells were skipping past it. It was just the shell on the carrier and the down hammer that through me, but like you said, that makes perfect sense and it's working as it should.