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Mossberg SA-20 Troubleshooting

Discussion in 'Mossberg SA-20' started by DHonovich, Sep 3, 2010.

  1. DHonovich

    DHonovich Founder Staff Member Administrator Sponsor "Philanthropist"

    Any issues, concerns or problems you may have with your mossberg SA-20; this is a thread for troubleshooting.
  2. cbshooter

    cbshooter .270 WIN

    Does anyone have any info on the SA-20 Tactical? My 930 SPX looks like is too much for GF.
  3. easyplinker

    easyplinker Copper BB

    PLEASE HELP!!!! Bought my sa-20 and took it out to our rage as soon as i could, had with me at the time a full box of ESTATE game and target load--2 3/4inch. 7/8oz.shot 2-1/2dram eq. muz vel 1210 fps.
    First shot jammed after firing due to the shot shell not clearing the chamber when ejected, causing the bolt to slam (jam) the shot shell so the next shell is unable to cycle,so naturally thinking brand new gun fluke, I chambered the next shell manually and shot it for a second time and the bolt never even moved. This proceeded to happen to every individual shot after that totaling 14 consecutive shots that not only didnt cycle rounds but the bolt never moved after being shot not allowing the shell to be ejected.
    Out of the box the gun had a mag. tube blocker from the factory requiring you to unscrew the tube cap and remove a 2 peice deal consisting of the blocker im guessing and a plastic circle with a hole in the middle and screw the cap back on,it said nothing about putting the washer type "thing" back in or how so I do not know if that is the problem.
    If anyone has even an idea of what the problem could be I would highly appreciate it as i love the gun and this flaw is crippiling my actual home defence gun
    I can try to provide more info if it comes to me i dont know if it matters but it is the model with the 20' barrel and fixed stock with no pistol grip and small rails on the tube cap.
    Again I am grateful for any kind of help at all, thank you.

    LAZY EYED SNIPER Overwatch Staff Member Administrator Supporter "Philanthropist"

    Welcome aboard.

    Is the Estate the only ammo you tried? If so, I would suggest picking up a few boxes of various brands/loads to see if you get any different results. Try to keep the muzzle velocity rating in the 1300-1400fps range. I have similar issues with low brass and cheap bulk ammo in my 930...
  5. BrianJ

    BrianJ .270 WIN Supporter

    Welcome to the forum. Sorry to hear you are having problems. I have the same gun and I have had some problems but most are now fixed. This sounds like more than an ammunition problem. I have never heard of the bolt and the action not moving at all. usually it moves but not far enough to eject and cycle the next round. I would check to see if the piston, tube and action are lubricated.

    Per the Mossberg manual, the gun only cycles reliably with 1 oz shot. This is true when new. I would try some 3/4 or 7/8 oz rifled slugs and then go to 1 oz shot. I use the Winchester AA #7.5, 1 oz, 1165 and 1200 fps and it works. I have also used Estate heavy dove #6, 1 oz. Use "High Brass" loads for starters. As the gun broke in, I could use lighter rounds (after 250 rounds or so)
    Do not use live rounds unless you are at the range and ready to fire. USE SNAP CAPS.

    I assume this is a brand new gun? It should probably be cleaned and lubricated and visually checked for any foreign objects in the action or sticking/binding/interference problems before firing.
    If you cycle the action arm does the bolt and carrier move fairly smooth and easy with spring tension?
    If it moves and locks open, does the bolt release button close the action fast?
    Using snap caps, can you manually load a shell from the magazine and eject a shell from the chamber?

    The plastic rod and washer in the magazine is a round limiter for hunting. It should not interfere with the operation of the gun at all except to limit you to loading 2 or 3 rounds in the mag tube.
    Can you load rounds into the mag tube? Do they load into the chamber manually?

    Post some pics of the piston and mag tube and the action open.
  6. easyplinker

    easyplinker Copper BB

    Thank you both for your responces any help at all is help I am grateful for...

    brain-I mainly use clp but did not lube any of the gun prior to shooting it, partly because i could visually see oil around the action and partly because I was very excited and impatiently i guess went as soon as could.
    -Yes the action cycle smooth but firm as it should from what i can tell
    -Yes it locks on the first round every time (i started to shoot one shot at a time after the problem continued)
    -Yes the release button works,slams shut firm,tight,every time.
    -I have never used snap caps so I cant tell you if they eject,load,or cycle
    -If you meant was the shell loading when i cycled the shot shell out? then yes as far as actually loading the gun in terms of being about to fire i have not seen any problems yet and unfortunatly i do not have any way to post pictures other then my cell phone this is really all i can think of for now
  7. BrianJ

    BrianJ .270 WIN Supporter

    It probably had enough factory lube for the first go round. Assuming the rounds are high brass at least 7/8 to 1 oz. or slugs, and if the action is not moving at all when firing, I think it means either the gas is not getting to the piston (blocked ports) or too much is leaking by the piston or (highly unlikely) the piston is not installed or not installed correctly.

    Have you had the cap and foregrip off to see the piston, spring and mag tube? I can take some pics of the parts on mine to compare if it will help.
    This is a weird problem for sure. It may have to go to the store, mossberg or a gunsmith.

    Have you tried slugs. they recoil more and may cycle the action.
  8. easyplinker

    easyplinker Copper BB

    Yes from removing the round limiter i had the cap and foregrip off so your pics could actually be very helpful and i have not tried slugs i didnt know you could with out a riffled barrel
  9. BrianJ

    BrianJ .270 WIN Supporter

    They make rifled slugs for smooth barrels. I have used Federal 3/4 oz. Slugs have noticeably higher recoil though. The Sabot (say-bo)slugs are made for the rifled barrels but I was using them in the beginning before I knew the difference. They say using the wrong slug is not as accurate but should not damage a smooth bore. I would not use slugs with anything but a cylinder bore or cylinder bore choke, possibly an improved cylinder choke. Dangerous. If you have the 20 inch tactical, that is a cylinder bore and OK. If the slugs don't cycle the action, there is definitely something wrong and it should be sent to Mossberg.
  10. BrianJ

    BrianJ .270 WIN Supporter

    cannot attach pictures.
    Have you figured anything out yet? I put 10 federal rifled slugs through my gun last night with the Improved Cylinder (IC) Choke installed. You don't need a choke unless you shoot trap or skeet. I do it to practice aim and control.
    Let me know if the pics are too simple or if you need more detail.
    apparently I cannot upload the pics as they are PDFs and too big. PM me an email address or an ftp site and I will send them.

  11. BrianJ

    BrianJ .270 WIN Supporter


    Finally figured out the problem with the pics. High Res, too big

    See if these help.
    All parts must be lightly oiled and must slide easily on mag tube. be sure the gas ports are open to the barrel using a pipe cleaner and solvent. Clean barrel and piston cylinder after ports. Action must pull all the way back and lock.
    When fired, gas will blow back the piston and piston hits action sleeve pushing action arm and bolt back. this extracts and ejects the shell. spring return loads another shell. (readers digest version, more actually going on)

    Let us know what you find out.

    Attached Files:

  12. old wanderer

    old wanderer Copper BB

    I also have a SA 20 Turkey Thug, with a 2 rd Choate extension. I dove me a bit crazy trying to get light target loads to get this gun to cycle.
    I had read on another forum that is you polished the chamber all would be fine...not true
    I polished my chamber, lubed my gun loaded it with some Win cheap shells, Bang, 1st one ejected right next to my foot, the nothing would cycle the gun.
    I put some 3" mag shells and it threw them 25 yards away....
    I had bought this gun for my daughter, for home defense, but ended up buying a youth 500. (She is just 5' tall) since this did not have my stamp of approval for a totally reliable gun.
    We are going to Front Sight NV to do a 4 day shotgun course, so I went out to the range to check the zero on my Benelli. I also brought the SA 20 (as I really like that little gun with the ghost rings sighs and fiber optics). I had bought a case of Rio #3 buck, so for the heck of it, I shoved 5 shells into the SA 20. Ran perfect. I ended up going through a box of 25 just because I was so happy to see this gun run normal.

    Tomorrow I will go and fids some 1 oz Win loads and runs 6 boxes through it to see if it breaks in right.
    Tonight I tore it apart and spray it down with Gun Scrubber, then lubed it with break-free. (Not my favorite lube, but I want it to wear down any high spots, then I will give it a more "slippery" lube.
    Need to shorten the stock by 1.5:so that midget daughter can shoot it. ( :? Guess this means I won't see much of it again, as daughter lives in Ft. Lauderdale, and I live in Washington. ) :cry:
  13. old wanderer

    old wanderer Copper BB

    Re: Mossberg SA-20 Troubleshooting:: Saga cont.

    Went to the range last night. Started with some WW 7/8 oz 1300 fps rounds...had 2 failure to chamber from the shell hang up on the top of the barrel entrance. Then tried a box of 11550fps 1 oz loads, ran good, finally broken open a box of Rio 7/8 oz 1250 fps loads, they also ran and fed without problem.

    I believe the fix for this gun was to soak it down with gun-degrease, then a light oil and run some shells through it. (i did a lot of rapid pairs, and the barrel got smoking hot).

    Now some of the metal is starting to wear and shine at contact points.

    Now to shorten it to 13" LOP so my midget daughter can shoot it.
  14. BrianJ

    BrianJ .270 WIN Supporter


    I do not know which stock you have but the pistol grip tactical stock has a 13" LOP. (1 inch shorter than the standard stock) I got mine with the pistol grip and bought the standard later. Sometimes Mossberg sells them separately. before you cut a stock at least check it out.
  15. old wanderer

    old wanderer Copper BB

    Well I have the "Thug" working to my liking. (Finally).
    The LOP is now 13" with a very nice recoil pad installed "(professionally)".

    In today's emails I received a very nice note from Mossburg in response to my questions about an alternate stock and light loads:

    Thank you for your email. we do apologize but at this time Mossberg does not sell any accessories for this gun. we haven’t been informed if they ever will or not given the gun is not made in the usa. It’s made in turkey so even we have limited parts for this type of gun. if anything should occur with the gun. it would need to be sent in for repair, to our repair center in Texas. also this gun is built to cycle 1oz or above shells only. No modifications can be done to shoot anything less. please call us at 1-800-363-3555 Monday thru Friday from 7am to 5pm if you have any other questions. Thank you and have a great day.

    Somebody should copy that quote and put is at the top of the SA20 board.

    I will be going to Front Sight and take the "Thug" along for my midget daughter to shoot. Bought a case of #3 Buckshot, 2 cases of Rio #7.5 shot and 100 Remington 5/8 oz slugs. The gun should be well broken in when we finish. (I will be shooting my M2 Benelli).
  16. Bobster

    Bobster .30-06 Supporter

    Just to clarify, you need to have a choke tube installed if the barrel is threaded for a choke. The barrel threads (and barrel accuracy) can be ruined and make installation of a choke impossible if the gun is fired WITHOUT a choke tube.

    A cylinder, skeet or improved cylinder choke tube should all be fine to shoot rifled slugs out of, maybe even a little tighter--refer to your owner's manual.

    PS: Knock on wood, my SA-20 Thug (with skeet tube) has eaten and spit out everything I've put in it, including some 40 year old bird shot in the 3/4oz-7/8oz size... :) I did take some time and smooth any sharp edges in the bolt and other SA parts.
  17. john797

    john797 Copper BB

    I just bought a SA-20 Tactical and have issues with it from the start.
    I started to clean it and found that I couldn't remove the barrel following the instructions in the user manual. I opened the bolt, removed the end cap, the tri rail, then the magazine cap. I slid off the forearm and eased the bolt closed. According to the manual I should now be able to remove the barrel but it won't budge. I then opened the bolt and tried but still no luck so I reassembled as it was.
    So I gave up on that and pushed two 2 3/4" field loads into the magazine and closed the bolt. The shell caught on the edge of the chamber and jammed. I had to hold open the bolt and shake the shell out. I removed the other shell and dropped a shell into the open chamber and closed the bolt with the same results.
    Any ideas on how I can get this thing working without having to send it off for repairs?
  18. BrianJ

    BrianJ .270 WIN Supporter

    Thanks, good catch. He said in the beginning he had a 20" barrel. I just assumed it was the cylinder bore tactical. I should have said you don't have to ADD a choke unless you are shooting trap or skeet. If the barrel is threaded you always need a tube installed to protect the threads.

    I actually had Mike Orlen thread my 20" tactical barrel for Remington chokes. I leave the improved cylinder (IC) in any time I am not shooting trap. That way I could put slugs through it if needed.
  19. BrianJ

    BrianJ .270 WIN Supporter

    I had the same issue with the shells not chambering. It ended up the elevator must have been bent and was not lifting the shells straight. See if it looks crooked. I did have to send it back to get the trigger group replaced (the elevator is part of the trigger group). There are other threads on this forum in the past with the same issue. Have a look and see if any look familiar.

    One thread had pictures of a broken elevator but I do not remember how it was resolved. Mine works every time now with 1 oz shot. I can also use 7/8 oz. Winchester AA with 1300 fps velocity (more power so the lighter load works). factory says only 1 oz shot works.

    I never had any trouble removing the barrel though. I would try a little light penetrating oil like Kroil (not WD-40) where it seats into the receiver and where the piston rides on the mag tube and let it sit a while. do not force it. If it has to go back, don't even worry about it. just include that problem it in a letter when you send it back.

    Call Mossberg Tech Support about both problems and they may give you some things to try first.

    Mossberg/Maverick gets them fixed but I know they are very busy.

    Good luck and keep us in the loop. any other questions please do not hesitate to ask, we'll try to help.
  20. FL-Boss

    FL-Boss Copper BB

    Do you have a picatinny rail install on your SA-20? If so.. that is your problem right there. It's the front screw that hold the rail on the barrel. It's seating too far down through the chamber and hitting the barrel, thus putting downward pressure on the barrel and preventing you from removing it. Ask me how I know :) I spend hours trying to figure out why I couldn't get my barrel off. Just loosen that front screw up a little bit and the barrel will fall off...
    jisco38 likes this.

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