Baretta 391 - Jamming Blues

Discussion in 'Technical Questions & Information' started by USP 45, Jul 19, 2012.

  1. USP 45

    USP 45 New Member

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    OK - I've only been getting 100 rds or less before she starts jamming. I've been told the loading gate could be an issue and can be replaced by Cole Gunsmithing of Maine.

    Yet, I've also had failure to eject and some ejected shells caught by bolt which can not be blamed on the loading gate.

    Baretta CS was not very helpful and even tried to blame the whole thing on my having the gun ported.

    Now, I did have a weight in the mag tube which I just removed along w giving the gun an annual cleaning. God willing, my jamming issues should be gone.:)

    Or it's my ammunition...:rolleyes:
  2. Helix_FR

    Helix_FR Active Member

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    Cleaning it may give you good success but I'm in with Beretta. Porting barrels can relieve the much needed pressure spikes in the barrel too soon causing it to short cycle. Unless you reload your own shells and you can either go to a faster powder or slightly more powder weight to make up for it I don't recommend it.
  3. USP 45

    USP 45 New Member

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    Well, I shot my best round of skeet and the gun operated flawlessly. Yet, this is only 50 rds. The porting is well beyond the two gas ports that operate the action. Rhino did the work as well as lengthening the forcing cone.

    I have 4 cases of Estate 9 shot, 1 oz loads which is light ammo.

    I also put the Rhino tube which is supposed to give the same feel as o/u. This replaces the end cap which is another factor. I shoot again tomorrow and all I really cleaned is the Piston & mag cap shaft. I have small plastic tool (Midway USA) that can bend and actually get into the two gas ports to ensure they are not plugged. Buggers are not easy to get to. :eek:

    I have about 2,700 rds through the gun so I have not taken the spring assembly apart yet. I lost the two wrenches as well so I don't quite know how I'm going to get it off. :rolleyes: I heard a T-shirt inside a 1/2" socket will work but I've never tried it.
  4. Hammerslagger

    Hammerslagger New Member

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    Helix_FR knows what he is talking about.

    When you ported the barrel you invited trouble. If the barrel had need porting, Beretta would have ported it and adjusted the barrel's gas port size accordingly.

    At this point you can find a gunsmith who is experienced in opening up the barrel's gas port(s) to compensate for the unneeded barrel porting, or you will likely be plagued by an unreliable gun.

    Here is a link to a possible solution: http://www.magnaport.com/
  5. Helix_FR

    Helix_FR Active Member

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    I understand that, but so is your pressure spike and its lost in the porting. Not all porting is bad but there are instances were the porting is too much. There are better ways to counteract recoil and flip than just porting.
  6. USP 45

    USP 45 New Member

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    I invite everyone to check out Rhino just google Rhino chokes. Their chokes are famous but their porting is excellent. Like magnaport and others, this tech has been around for quite some time.

    Almost every 12 ga. I see on the skeet field is ported in some way or another. Many 20 gauges as well.
  7. jack404

    jack404 Former Guest

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    this can be resolved , but be honest when you do it ...

    if you load or know someone who does , get em to do a over pressure load and see if that fixes part of the problem , the 100 round or so then jamomatic is cleaning simple

    not all guns are designed to shoot a lot , just to shoot and some build up gunk fast

    and i've seen magna port jobs cause issues

    porting is good i have a few done myself , but on semi's , its iffy .. they balance the inertia rates so fine to not need huge springs and need re-enforced area so they can make em as light as possible ... porting changes all that

    the finer tuned the gun , the more pronounced the issue will be , a tank ( not a finely tuned one) will take it fine , a glock is a tank a S&W cop auto is a tank , you can beat drop em port em fire junk ammo , they aint fussy , port them .. nicer ones , stay away

    go a 1911 that was made to shoot 1000 rounds it was a design requirement it met with ease
    Last edited: Jul 23, 2012
  8. Helix_FR

    Helix_FR Active Member

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    Many of those guns are not gas guns. Double-no problem, short recoil- no problem.
  9. Hammerslagger

    Hammerslagger New Member

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    When a Beretta 391 gets a barrel porting job, one or both gas ports to the gas cylinder usually have to be made larger. Most shops that port Beretta 391 barrels are aware of this, and have worked out their own trade secret way of compensating for the altered (reduced) pressure and time curve that the porting near the end barrel causes.
  10. USP 45

    USP 45 New Member

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    Just got off the phone w Rhino and they pointed out all the champions who use their porting w/o incident. They are pointing toward the loading gate carrier which is,a known fault among 391s.

    He also brought up the recoil spring in the stock which has been an issue with guns that may have sat around for any length of time dirty. Everyone wants me to send them the gun and they will figure it out for me.

    Rhino wants approx $90 for loading gate issue but until I get FTFeed issues, I'm not going to throw money at it. I'll see how well she runs tonight.

    Rhino did confirm that gas guns can be temperamental and a weight in mag tube might have been the issue. Let's see how well she runs w/o it first. Then maybe add it later.

    1001 thanks for everyone's input. Will report how well she functions tonight.

    Side note: Angle porting said to take 5 coils off recoil spring in stock so bolt carrier comes back farther to properly eject shell and they bevel the loading gate barrel ramp.

    Wish I had saved up for o/u.
    Last edited: Jul 23, 2012
  11. Hammerslagger

    Hammerslagger New Member

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    Shortening (as compared to installing a lighter spring) a recoil spring is often bad practice. There are several possibilities that I do not have time to go into now. May try to write more later.

    For now, make sure that your gun is well lubed and starts off clean for the day's shooting. Time/pressure curves are complicated things. The factory design for this gun allowed for a wider range of time/pressure curves than is possible AFTER THE BARREL WAS EFFECTIVELY SHORTENED BY PORTING.
    Last edited: Jul 23, 2012
  12. USP 45

    USP 45 New Member

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    Ok, 100 rounds later and I had 3 malfunctions. The empty shell hangs up w the bolt. Is this a failure to eject or a feeding issue? My skeet Cpt handed me two STS Rem shells for a double and it fired fine.

    I will try to bring a camera w me next time so I can get a picture of exactly what is happening. One time the bolt caught the empty shell which stuck in the action. All I,had to do was pull it out and the gun was ready to go.

    I also noticed that some shells were landing at my pops feet. Easier to see when someone else is shooting.

    I suppose I could take the the spring assembly apart if necessary. It's supposed to be a 5,000 rd service and I've only shot approx 2,800. I'd like to stay away from the springs if possible.
    Last edited: Jul 23, 2012
  13. Hammerslagger

    Hammerslagger New Member

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    I have done a little more research since yesterday, talking with several knowledgeable individuals who are experienced with the Beretta 391 series guns and the porting of them.

    I think that the bottom line here is that the altered barrel/ammo combination is not cycling the action reliably.

    Gas operated shotguns often do not well tolerate low pressure loads. Today, most shotgun "field and target" factory ammo is loaded to about 25% higher pressure than 50 years ago. Also, the propellants produce a different pressure/time curve to optimize performance in "gas guns".

    From what you describe the action is cycling too slowly to get the spent shell casings out of the gun properly. I strongly suspect that it is going to take different ammo that produces higher pressure for a longer time, or a replacement unaltered barrel to solve this problem.

    The cycling of all self cycling (e,g. semi auto) actions is opposed by the friction between various moving and stationary parts of the gun. Proper lubrication and cleanliness can reduce it.

    Also, it is opposed by the hammer's mainspring which must be compressed during cycling.

    The cycling is also opposed by the recoil spring system; BUT THE RECOIL SPRING SYSTEM ALSO HAS TO RETURN THE BOLT OR SLIDE BACK INTO BATTERY. Thus, installing a lighter recoil spring of the correct length, or, even worse, lightening a recoil spring by shortening it can create problems of letting the bolt slam excessively hard against the receiver, and most importantly, failing to properly return the bolt into battery. The preceding statements are general in nature. I have no experience modifying the recoil system of the Beretta 391. However, I agree with you in staying away from recoil spring modifications, if possible.
  14. USP 45

    USP 45 New Member

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    I agree. The ammo is 1 oz 9shot and it must be too light to cycle the action reliably or at least not when dirty. Some shells fell at my fathers feet. The STS shells cycled well but I should have looked to see where they fell.

    I too have talked to as many "experts" as I can. Your - return to battery issue is a valid concern and shortening the recoil spring which normally shorten w use could result in unnecessary force or slamming of bolt group. However, this is what "Angle Porting" does to their custom guns along w beveling to increase reliability.

    Rhino wants $85 to clean gun, Cole $120 - might be cheaper to just buy better ammo.

    Problem: I still have 4 cases of the Estate ammo left. Kinda like trying to make kids eat their spinach. :eek: They are going To get a steady diet of it one way or another.

    I don't recall it having a problem years ago but then again, my memory is not what it used to be. ;).

    Reloaders often have o/u so they can shoot low velocity loads. 391 was designed to shoot 3" and lighter. Browning tried two different gas pistons for light or heavy loads. Even the Benelli Blackhawk can't shoot 1 oz loads.

    Is the factory recoil spring too stiff for light loads ? Is this why Angle Porting cuts 5 coils out ? It certainly sounds like my problem w go away if bolt group traveled further into stock to aide ejection.

    This problem may not be inherent in the porting but simply be on the edge of the pressure necessary to cycle the action.

    I believe I now understand why some competition guns are 2 3/4 only. You give up the high end to improve performance on the low end. Very, very frustrating.

    Damn front sight broke in half on station one. I know your not supposed to look at it but I was raised on bullseye where sight picture was the Holy Grail. Now, I feel a bit like Monty Python - coconuts n all.:D
    Last edited: Jul 24, 2012
  15. USP 45

    USP 45 New Member

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    OK - just got off phone w Cole Gunsmithing from Maine. They are sending me a 2 Spring set, one lighter, one heavier. God willing, this will solve the problem.

    A properly running 391 should eject 6-8' from shooter. If less, than bolt group is moving too slow so go w Red Spring set, if too fast, then Blue Spring set both are $16 w $5 S&H.

    If not, the loading gate is 81.99 total. Which I don't think is the issue. And I have enough money into this gun in the first place.

    If I had it over, I w have bought an o/u.
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