Rounds will no longer go into battery on .40 Gen2 Sub2k -- damage from overpressurized round?

Discussion in 'Sub9 and Sub2000 Rifles' started by Snuggs, Jul 25, 2017.

  1. Snuggs

    Snuggs New Member

    4
    Jul 21, 2017
    Hi, new member, longtime Sub2000 owner. I was plinking at the range today, shooting some crappy leftover Perfecta ball ammo. After a few rounds I noticed my sub2k refused to go into battery. Thinking it was a simple malfunction or stuck case, I reracked the bolt to try to chamber another round. Same problem again and again with each round. When I looked at the last spent casing, I noticed it was very slightly mushroomed. Also, trying to rack my memory, I *think* the final round felt a little hotter than the ones before? By the same token, I really, really REALLY dissuade anyone here from using Perfecta. Rounds would randomly hit four inches off paper in every direction imaginable at only 25 yards. If it was indeed an overpressurized round, can't say I'd be surprised. In hindsight I probably should have stopped shooting after seeing just how haphazard the accuracy was.

    Anyway, with a visual inspection I notice what could be some damage to the face of the hinge where it connects with the barrel/chamber? The barrel seems to be ok looking through it, but I suspect the chamber may have taken some structural damage and is no longer within spec to hold the round :(. Luckily the bolt head seems to be ok, and the trigger and action are all functional. I've provided some photos to give a better look:

    http://imgur.com/a/bszXs

    I don't want to go through the hassle of sending my sub2k in to Keltec -- I'm already in mourning that it's out of commission for the first time ever in its 18 months of life. My question is, do you guys think it's likely damage to the hinge, the chamber/barrel, or all of the above? Or perhaps something else entirely? Would it be worth it to see if the warranty would cover Keltec sending me a replacement hinge?

    EDIT - posted this in a response after fiddling with the rifle some more:

    After cleaning and lubing the rifle thoroughly and racking a few snap caps into it, it seems to be going into battery now. Rounds are extracting fine as well. However, I'm a little concerned still as it seems that perhaps the barrel liner/rifling shifted backwards towards the chamber, and that was what was causing the rounds to hang up as the case ridge was hitting it prematurely. I suspect that it effectively shortened the length of the chamber, perhaps. (compare the liner in the first set of images/how the round sits in the chamber with this second set)

    http://imgur.com/a/VMjUI

    I think hammering home rounds and adding a little lubrication help shifted the barrel liner back into position. I guess the question is, is this gun still safe to shoot now? I don't want my barrel liner blowing out the end of the muzzle next time I take my sub2k to the range.

    I can't find anywhere online of this happening to another sub2k owner, though. I will admit the gun was fairly dirty during my range session, but not absurdly so. Maybe 350+ rounds worth of buildup since the last cleaning. Most of that was white box, which obviously can be quite filthy. Perhaps a dirty chamber and the blast of a slightly overpressurized round caused the barrel liner to shift? The barrel itself feels sturdy and nothing appears loose or out of whack, either. I have a business acquaintance that works at a local indoor range complete with an on-site gunsmith who owes me a favor. Might go cash it in and ask if the gunsmith can take a look at it just in case. Still not totally confident to shoot it again.
     
    Last edited: Jul 26, 2017
  2. 850sub

    850sub Well-Known Member

    Nov 7, 2012
    Pensacola
    Pictures will help us help you.
     

  3. Snuggs

    Snuggs New Member

    4
    Jul 21, 2017
    Sorry, I made an album on imgur but it didn't hyperlink: http://imgur.com/a/bszXs
     
  4. haugrdr

    haugrdr Well-Known Member Supporter

    Jan 4, 2008
    Daytona Beach
    Huh...anything I see in your pictures looks like "normal" wear and tear. Most subs can look much worse in that area. From your pics, I see nothing to call for sending it back to Kel Tec...the chamber is probably filthy, clean it up, lube it up and take it out shooting again. Use better ammo. Let us know how it goes.

    I'll move this to the Sub 2000 forum, it'll get seen better.


    (BTW, I dread trying to shoot the 10 boxes of Perfecta I have. Yikes!) :shtf:
     
    Last edited: Jul 26, 2017
  5. Snuggs

    Snuggs New Member

    4
    Jul 21, 2017
    Much appreciated. I actually had a buddy almost berating me for buying it in the first place. I know Perfecta has a very mixed track record, but I never had major issues outside of the odd flyer before today. I only had ~40 rounds left in the box, but needless to say I trashed it.

    And I agree, I can't notice any kind of major damage or deformation after looking closer. After cleaning and lubing it thoroughly and racking a few snap caps into it, it seems to be going into battery now. Rounds are extracting fine as well. However, I'm a little concerned still as it seems that perhaps the barrel liner/rifling shifted backwards towards the chamber, and that was what was causing the rounds to hang up as the case ridge was hitting it prematurely. I suspect that it effectively shortened the length of the chamber, perhaps. (compare the liner in the first set of images/how the round sits in the chamber with this second set)

    http://imgur.com/a/VMjUI

    edit: can't find anywhere online of this happening to another sub2k owner, though. I will admit the gun was fairly dirty during my range session, but not absurdly so. Maybe 350+ rounds worth of buildup since the last cleaning. Most of that was white box, which obviously can be quite filthy. Perhaps a dirty chamber and the blast of a slightly overpressurized round caused the barrel liner to shift? The barrel itself feels sturdy and nothing appears loose or out of whack, either. I have a business acquaintance that works at a local indoor range complete with an on-site gunsmith who owes me a favor. Might go cash it in and ask if the gunsmith can take a look at it just in case. Still not totally confident to shoot it again.
     
    Last edited: Jul 26, 2017
  6. buzzsaw

    buzzsaw Grand Poobah Supporter

    Sep 7, 2004
    Georgia
    Do not shoot that rifle again until you have had a gunsmith look at it!

    The barrel and chamber are a single piece of steel. It should be "impossible" for the rifled portion of the barrel to move relative to the chamber. It is possible, however, that there was (is still?) a fragment of a failed case in the chamber. I have had case failures that left a ring of brass in the front part of the chamber which prevented the next round from chambering. For me, it's only happened a couple of times, and not with straight-wall, but with bottle-necked cases (.223, and .357 SIG). The ring of brass appeared to be cleanly cut from the case.

    You mentioned that the last case was mushroomed. This might happen if the case was extracted while the pressure was too high or was not fully in the chamber when it was fired (the case of the round before this one might be interesting). If you still have the case, see if it is the same length as unfired or normally fired brass. If it is short, some of it could still be in the chamber. If that is what happened, there could be a machining flaw in the chamber-likely a groove caused by an imperfect chamber reamer. This will look like one or more rings gouged in the chamber, and it can cause the front of the case to get stuck, and then ripped off during extraction, leaving a ring of brass in the chamber. This, and an out of spec chamber, is what caused the failure in my .357 SIG (the .223 was apparently just a random bad case). Looking at your pictures, particularly that of the chamber in the second group, I can't rule out some brass still stuck in there. The case mouth of a chambered round is supposed to be against the ridge at the front of the chamber, this is called "headspacing" and is a critical, safety-related dimension. I would expect that ridge to be fairly well machined and smooth. Yours shows more irregularities than usual.

    The round in your first set of pictures is definitely and obviously too far out. I went and checked mine, and the round in your second set of pictures, while better, is still too far out. The front part of the extractor groove should be flush with the back of the chamber. You shouldn't see that much case wall. All you should see is the rim and the groove. Something is still keeping the rounds from fully chambering and it needs to be fixed before you shoot the rifle again. You also should be able to smoothly rotate the round in the chamber.

    Do not shoot this rifle until you have had a gunsmith look at it! If there is still a ring of brass in there, or the chamber is not cut correctly, this can cause it to develop excessive pressure when fired. Forcing a cartridge into a chamber that is too tight, or too short, can constrict the bullet in the case. This will cause excessive pressure, since the bullet is too hard to get moving. This is dangerous, and not worth the risk.

    Take it to the gunsmith. He will have the tools and knowledge to properly examine and measure the chamber, as well as remove any case fragments. If yours proves to have a defective chamber, Kel Tec will want to know about it.

    Don't fool around with this, you could have a catastrophic failure and be seriously injured.:eek:

    buzzsaw-By the way, Welcome to theKTOG!
     
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  7. Snuggs

    Snuggs New Member

    4
    Jul 21, 2017
    Thank you very much for the obviously expert advice. I suppose you more or less have confirmed my fears, but laid it out in a way that I wasn't entirely informed on. The headspacing issue is one that ran past my mind, too. I knew something was fishy when it looked like the rifling had shifted and allowed the rounds to start chambering again. I can definitely see an outlined ring of brass down in the chamber when I shine a light down in it, too.

    Unfortunately, I didn't see the round that was fired before the final mushroomed case. I could potentially return to the range tomorrow and attempt to dig it out of the brass bucket and see if I can find one that was sheared off like you're saying. I'm betting it's in there somewhere.

    I'm really hoping it's not an out of spec chamber. I've put probably 1,000 rounds or so through my sub2k in the last year. Would an out of spec chamber allow me to fire that many rounds before a failure like this? I'm still leaning towards a defect with that ammo, especially knowing how it was flinging rounds out of the barrel like it was. About two mags prior, it was firing winchester white box like clockwork. I only got maybe 10 rounds into the Perfecta before the failure.

    Thanks for the welcome and thanks again for the information. Definitely gonna swing it by the gunsmith tomorrow and see what's up. I'll report back with the diagnosis. :wall::wall::wall:
     
  8. Bagger

    Bagger Member

    47
    Aug 13, 2013
    Coastal South Carolina
    Sorry to hear of your problem. If you still have doubts about it send it back and it will be taken care of.

    At our range there have been thousands of rounds of Perfecta fired. No problems with any of them. Most cheap range ammo is dirty stuff. You have to everything fairly clean and lubed to run dirty ammo.
     
  9. KT9mm

    KT9mm Active Member

    148
    May 31, 2016
    Buzzsaw - Thanks for your sharing of knowledge. I have heard of a number of case failure modes, but never ran across the one you describe. Thanks! Gives us all something to look for with any of our firearms, especially our necked round toys.
     
  10. poppo

    poppo Well-Known Member

    448
    Jul 3, 2008
    I agree with the post above that you may have a partial case stuck in there. It should be easy to spot with a good flashlight. It also should be not that hard to get out.
     
  11. buzzsaw

    buzzsaw Grand Poobah Supporter

    Sep 7, 2004
    Georgia
    Since it's not totally relevant to the OP's problem, I didn't want to go into how my .357 SIG chamber was out of spec and confuse matters earlier. Its shoulder was a millimeter or two further forward than it was supposed to be. Since .357 SIG headspaces on the shoulder, the rounds would have gone in too deeply, and were it not for the extractor holding them to the breech face, they might not have fired at all, due to the firing pin not reaching out far enough. This meant that the cases were not being supported correctly. The shoulder stretching forward when the round was fired while being held back by the extractor combined with the ring in the chamber is what cut my brass. Kel Tec replaced the defective barrel, and the replacement has been fine.

    There is less that can go wrong when cutting a straight-walled chamber. Since the OP says that he put many trouble-free rounds through the rifle, it's likely the chamber is in spec or pretty close. Maybe it has a rough area due to rings and/or reamer chatter when it was being cut. Using steel-cased ammo, especially older lacquer-coated, can leave difficult to remove deposits in the chamber that can cause brass cases to stick. Another possibility is that it tapers smaller near the case mouth. This could cause higher pressure. Maybe it's just a lot of crud buildup near the case mouth that had the same effect. It's also possible that it was just a bad case that failed, leaving a ring of brass in the chamber. It's possible that it happened early on when shooting the Perfecta ammo, and this was also causing the inaccuracy. The gun may have been forcing rounds into the chamber despite this obstruction. This would have had the effect of a crimping die on the rounds, or it could drive the bullet deeper into the case. Either would have caused higher than normal pressures, and it would likely be inconsistent, resulting in widely varying pressures, velocities and thus trajectories. Bullet damage is also possible. None of this is good for accuracy. I would also expect that fired cases would exhibit scratches, scrapes and other damage at the case mouth.

    The trick to getting a stuck brass fragment out is to take a bronze bore cleaning brush and start it into the barrel, then break the rules and pull it back out. The bristles will expand out when the direction is reversed, causing them to dig into the brass and grip it. It might help to put some penetrating oil in the chamber first, especially if the ring has been pounded in by repeated firings. Even if you get it out, it would still be prudent to have the gunsmith check the gun out to confirm the chamber measurements and condition as well as to make sure that this episode didn't damage the gun.

    Safety is paramount, and peace of mind is important.

    buzzsaw
     
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  12. guru2sum

    guru2sum Well-Known Member

    Apr 30, 2005
    Mad City, Wisconsin
    Good point. I had this in a SU-16. The steel-cased worked fine, but the brass fired after stuck. So I originally thought it was the brass that was the problem. The chamber needed a good cleaning.
     
  13. TNTRAILERTRASH

    TNTRAILERTRASH Active Member

    251
    Aug 27, 2015
    I can testify I have had the jacket shred off Perfecta 9mm on 3 or more occasions. It landed on the table in front of me. Large fireballs out of my Glock 17.It leaves gold flecks in the guns. The range owner said that Perfecta spits the jacket onto the floor too. Walmart isn't carrying it any more. I won't go out of my way to buy it online as it is over priced.

    https://m.facebook.com/story.php?story_fbid=1174683502563214&id=113968675301374

    Just a public service announcement: we have had 2 firearms blow up and 1 come close to blowing up over the last 2 weeks. Perfecta ammo 40 S&W is over pressured or could be too thin of brass -do not use in unsupported barrels such as Glocks and Spring Field XDs. You can see the bulge in these casings. We have seen it damage a couple guns and fire out of battery.

    It was a Gen 4 G23 and XDS mod 2 but any firearm with an unsupported barell should be careful when using high pressured ammo
    Like · Reply · Report · Jun 16, 2016
     
    Last edited: Aug 10, 2017
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