Berretta 3901 Failure to Chamber

je2140

My brother has a Berretta 3901 12 gauge auto with a few hundred rounds thru it that recently began failing to close the breech when loading automatically, has anybody heard of this. Using factory clay's loads from two manufacturers and it was failing to load the 2nd shell about 50% of the time. The breech can be forced closed without much effort so the shells don't seem to be the problem.

317wc

Well you don't give a us a lot of info but right off the bat I'd say dirty, you say that it won't load the second round about 50%, and that the bolt can be "forced closed" without much effort, what does that even mean? How long has it been since its been cleaned?

je2140

It's always been cleaned after every time it has been shot

rwfixem

still dirty. Had guys tell me "I cleaned it". Their clean is to push a patch down the bore.

317wc

I agree, it sounds dirty, these are gas operated guns, is the gas port free and clear? Sorry I'm not much help but I agree with rwfixem, a lot of people "clean" their guns by running a patch down the bore or squirting some guncleaner in the action.

EDIT: clogged gas port could be not letting full charge of gas back to cycle the action. The empty shell is light and will kick out without much problem, loaded shell is much heavier, coupled with a dirty action, will not allow bolt into battery. This is only my theory.

machine gun moran

If there's not a problem with the empty clearing the gun, the gas port doesn't figure into it. It's the forward stroke, and sluggish loading orients towards gunk or the return spring.

toad67

Doesn't it seem odd though that it does it on the automatic, or 2nd shot only? You'd think that if the action was open and you put in the first shell and pushed the button that it would do it then also.

bambambam

I've had a lot of Beretta auto loaders over the years, never had this model, and if they are doing what you say...it needs cleaned better.

Check to be sure the spring/plunger in the stock is clean & oil free. Clean the mag tube really good that the action slides on & put a LIGHT film of oil on it. I'm guessing that the 3901 is strictly gas, so be sure and run a pipe cleaner through the gas holes like mentioned above.

After you get all that checked put one drop of oil on each side of the bolt where it slides in the receiver. If the gun doesn't not snap shut forcefully when done you may need to take the spring out of the stock & investigate.

If the gun will cycle, but not go into battery completely.... 9/10 I've had a cleaning issue with mine.

booger

I duck hunt with a 3901 and it's the return spring inside the buttstock. This is an annual teardown operation due to operating conditions.

It's not intuitively easy like an 870, but do it once, and it's simple after that. Only a few hundred rounds? Well the factory grease inside the spring/tube is not what I would use, too heavy in my opinion.

I used the "how to" instructions at shotgunworld, within the Beretta category. I'm not sure that the forum guidelines will allow me to post a link here, but it was a big help.

je2140

Thanks for the feedback, excellent suggestions to try