G20 and G29 going to slide lock with a round in the mag

Discussion in 'The 10 Ring' started by Big Sam, Apr 7, 2012.

  1. Big Sam

    Big Sam

    Messages:
    310
    Likes Received:
    4
    Joined:
    Jul 13, 2007
    Location:
    PA
    This one has me stumped. I've been shooting all manor of Glock's for 15 years without issue. 3 months ago I picked up a G20SF and a G29SF new. Great guns. But I have developed this strange problem in both guns. The gun will go to slide lock with one round still in the magazine (any of a number of mags). I can pull back on the slide to feed the round but it's at slide lock just as though the mag was empty. It happened 3 times this morning with the G29 SF. At first I thought my thumb was hitting the slide release during recoil but that is not it. If the nose of the bullet points up a little bit in the mag, it will allow the front of the mag follower to rise up enough to engage the slide stop lever .

    This is with both guns, only on the last round and the guns run 100% otherwise. Both guns are 100% stock save but the G29 mags have the Pearce +0 extensions on them.

    It has happened with factory and reloads. I shoot mostly reloads though.

    Any ideas guys? I emailed Glock last Monday but have not heard back from them.
     
  2. attrapereves

    attrapereves

    Messages:
    2,099
    Likes Received:
    0
    Joined:
    Sep 11, 2011
    Location:
    Midwest
    I've made a post on here before concerning two different styles of 10mm magazines. One style makes the cartridge nose up more than the other. This may be the cause of the problem.

    Let me find my posting...

    EDIT: https://www.glocktalk.com/forums/showthread.php?p=18750781

    I've had two FTFs with my G29 and both were with the magazine style on the left. Coincidentally, this mag is the one that causes the bullet to feed at a higher angle.
     
    Last edited: Apr 7, 2012

  3. dpadams6

    dpadams6

    Messages:
    2,192
    Likes Received:
    545
    Joined:
    Jan 5, 2010
     
  4. WeeWilly

    WeeWilly

    Messages:
    18,800
    Likes Received:
    29,818
    Joined:
    Nov 12, 2011
    Location:
    Idaho
    I have had this exact symptom when I had a broken stop lever spring. For whatever reason the last round in the magazine would cause the lever to come up and engage the slide.

    Check that the spring that holds the stop lever is in one piece and is under the pin (under the locking block), thus putting down tension on the lever.

    If you don't know what I am talking about (very possible with my terrible explanations), just make sure the stop lever has a down tension on it when the magazine is out of the gun (i.e. push it upwards to the position it is in when the slide is locked back and let go, it should snap back down).
     
  5. Any Cal.

    Any Cal.

    Messages:
    442
    Likes Received:
    1
    Joined:
    Oct 27, 2008
    What willy said, and also make sure the cartridge nose is not hitting the slide stop on the way up...
     
  6. Big Sam

    Big Sam

    Messages:
    310
    Likes Received:
    4
    Joined:
    Jul 13, 2007
    Location:
    PA
    View attachment 224356 Thank all our guys for your input. It gave me things to check and review. If the picture will turn out, you can see that the part of the follower that hits the slide release lever is quite low on the G21 mag (on the right) and is flush with the top of body of the mag on the G20 mag. In both cases with one round in the mag. In fact, with a round in the mag, the G20 follower is touching the slide release lever in this natural state. Anything that might raise it a bit... and the slide is locked back. On the G21 you can see it's quite recessed and that prevents the problem all together. At least that's what it seems to be. It looks like a marginal Glock design but that's hard to believe after all these years of them making 10mm guns. Think I'll give Glock a call tomorrow.
     
    Last edited: Apr 8, 2012
  7. blastfact

    blastfact

    Messages:
    1,726
    Likes Received:
    70
    Joined:
    Aug 15, 2011
    Location:
    Oklahoma
    I had this happen with my G20 yesterday. Except it was the 11th round that the slide lock engaged. The slide lock barely caught the edge of the slide. I shifted my grip with the weapon still pointing down range and the slide slammed home.

    In my case I was on the last 50 of 300 rounds of nuclear reloaded ammo in the big 10. I wrote it off to a loose grip / limp wrist. The round was not any hotter than the rest. I was just getting tired. I shot 1K rounds yesterday, including 9mm, .45 acp, .357 and the big 10.

    I'm going out later today. I am going to work with the new M&P 9mm. But the G20 will be there also. :)
     
  8. WeeWilly

    WeeWilly

    Messages:
    18,800
    Likes Received:
    29,818
    Joined:
    Nov 12, 2011
    Location:
    Idaho

    I finally got a minute and checked my brand new G20 magazines (like 350 rounds each shot through them), they look exactly like the magazine on the left of your picture.

    The little triangle that has "2" on it sits flat with the ledge with one round it in and is up above that ledge by about 150" when the magazine is empty.

    So I think your magazines are fine.

    If the stop lever spring is intact and under the pin (under the locking block, thus providing down tension on the lever), I guess it is possible the little triangle on the stop lever (that engages the magazine follower when the magazine is empty) might be bent down some, causing it to engage that little triangle near the "2" too early.

    Maybe a picture of your stop lever out of the gun might help. One that shows where the little triangle is relative to the rest of the lever.
     
    Last edited: Apr 9, 2012
  9. ViennaGambit

    ViennaGambit

    Messages:
    1,197
    Likes Received:
    240
    Joined:
    Dec 19, 2009
    I don't mean to insult your intelligence, especially since you've been shooting for so long, but did you double check to make sure the slide release spring is under the correct pin?

    Its easy when putting the locking block pin back in to not put the spring under it....

    This can cause the slide to lock back with one round left in mag - happened to me once and I couldn't believe it took me a few days to figure out what I had done.

    With the slide off, when you lift the slide release up does it snap back into place?

    Here is a thread on the issue with pictures:

    https://glocktalk.com/forums/showpost...29&postcount=3

    Good luck.
     
    Last edited: Apr 9, 2012
  10. Big Sam

    Big Sam

    Messages:
    310
    Likes Received:
    4
    Joined:
    Jul 13, 2007
    Location:
    PA
    Insult my intelligence? That's pretty hard to do some days :supergrin:. The guns are put together correctly. Just to make double triple sure I took my G21 apart and compared. All is well. The problem I am having seems to be a recurring one that usually just goes away. Here is an earlier thread I ran across that explains more of the problem another person had.

    https://glocktalk.com/forums/archive/index.php/t-1388430.html

    I also compared the follower on my G17 and it's identical in it's relationship to the slide release as my 10mm Glock's. I'm also not so sure I'm not the cause of the problem with my thumb. The thread has a great way to test that and that's just to shoot with my left hand and see if the problem goes away. The other issue is half of the mags I used last Sat were brand new and that seems to be part of the problem. If this ever gets fully figured out it might make a good sticky. More to come. Thanks for your good advice guys.
     
  11. 4949shooter

    4949shooter

    Messages:
    10,854
    Likes Received:
    1,683
    Joined:
    Aug 14, 2006
    Location:
    New Jersey Republik
    It seems like a bit of a coincidence that this is happening with both guns. It is making me think you might be changing your grip when the mag gets lighter, and down to the last round.

    Have you tried letting someone else shoot your guns?
     
    Last edited: Apr 10, 2012
  12. Big Sam

    Big Sam

    Messages:
    310
    Likes Received:
    4
    Joined:
    Jul 13, 2007
    Location:
    PA
    I'm usually the "someone else". I am going to shoot the guns left handed and see if that changes the problem. You also surmise correctly that my hand moves around some with the recoil of a 10. I ordered a stick on Raptor Grip for the G29 to keep my hand from moving in recoil. Should have a better idea on Sat. Thanks.
     
  13. pistolpete10mm

    pistolpete10mm

    Messages:
    68
    Likes Received:
    0
    Joined:
    Feb 28, 2011
    Location:
    Belgium
    This is what I posted a while ago about a similar problem, it had to do with the +10% mag springs, but what caused the problem is here not so important, what is important is the solution I found (and my G20 has been running flawless ever since), check it out:

     
    Last edited: Apr 10, 2012
  14. 4949shooter

    4949shooter

    Messages:
    10,854
    Likes Received:
    1,683
    Joined:
    Aug 14, 2006
    Location:
    New Jersey Republik
    Good luck Sam. Let us know how it works out.
     
  15. G29SF

    G29SF

    Messages:
    377
    Likes Received:
    21
    Joined:
    Oct 24, 2011
    Location:
    Highland, IL
    I too have had issues with the slide locking back with one left in the magazine. A few months ago I did some inspecting and came to similar conclusions. With one round left in the mag, the cartridge can nose-up which allows the plastic piece under the cartridge (sorry for my lack of proper terminology) to raise enough to lock the slide. How I did this was locked my slide back then inserted a mag with one snap-cap in the mag. As I slide the mag in the well, I watched the engagement of the slide lock. I had to release the slide and hold the slide back to watch everything work. Until now, I did not notice the different mag styles. I too have one of each. I will pay more attention if one locks the slide back more than the other. Grinding the tab down a little is sure to work and I plan on doing that soon. Ever since I got my G29SF, I have not shot my G20SF much so I don't know if the G20SF has similar issues. I will start shooting both and also shoot the longer mags in the G29SF as well. I really want to get to the bottom of this. Things I do know... It is NOT grip and/or limp wrist issues. I have shot 1000s of rounds through both of my 10mm guns and ONLY have and issue on the LAST round. It is NOT an install/ping/spring (whatever) issue. This IS a magazine issue. The mag is locking the slide back with one round left in the mag. I have read about others that have had this problem but never bothered to respond. Most replies to them were using the traditional grip/wrist yada, yada, yada answers. It doesn't take too much thought to realize it is something else when it is always the last round. Not a coincidence.
     
    10or45 likes this.
  16. Jitterbug

    Jitterbug

    Messages:
    877
    Likes Received:
    19
    Joined:
    Aug 27, 2002
    With 1911's when the slide locks back on the last round I always think of the slide outrunning the magazine spring and it's usually fixed by tweaking the recoil and mag springs to work in harmony.

    I think Pistol Pete might have the solution.
     
  17. Big Sam

    Big Sam

    Messages:
    310
    Likes Received:
    4
    Joined:
    Jul 13, 2007
    Location:
    PA
    It appears our friend from New Jersey wins the prize! Rats. I thought I was smarter. I took the G29 SF to the range today. When I shot last week it was very cool. Today was warm & sunny. So I took 100 practice rounds and loaded them into 4 G29 mags and one G20 mag. I only loaded 3 rounds each time so as to give maximum chance for the slide locking with a round in the mag. The "someone else" was my left hand. A couple dozen times firing left handed I had NO failures of any sort. The slide only locked back when the mag was empty. I then did about a dozen mags right handed and again, no failures of any sort and the slide only locked back when the mag was empty.

    I noticed last week that the gun seemed to move around more than unusual. I always shoot outside and bought my 10's just this past Jan. Today with warmer hands and more natural traction/strength, I had no problems. I'll take out the G20 next weekend and duplicate the test but I'm pretty sure the verdict is in. There may still be other tendencies with new mags or other followers. Don't know. These are my first 10's and my first SF's. I'll do more testing... Lot's, they are great guns. May have to start taping my thumb down though :embarassed:

    Thanks again for your help and suggestions guys. Hope this is fixed now.
     
  18. 4949shooter

    4949shooter

    Messages:
    10,854
    Likes Received:
    1,683
    Joined:
    Aug 14, 2006
    Location:
    New Jersey Republik
    It's much easier to be objective when you are removed from the situation. Glad to be of help! I hope your problem is solved, Sam.

    Best of luck with your G20 as well.
     
  19. ModGlock17

    ModGlock17

    Messages:
    10,212
    Likes Received:
    10,850
    Joined:
    Dec 18, 2010
    Location:
    DisneyWorld
    Lots of people have issue with this. Some even suggested that the thumb inadvertently hit the slide lock tab during recoil, to which I was impressed if thumbs are so good that they can detect a remaining round in the mags. Mine isn't that good. Lol

    As I recall, the common denominator in all these incidents are NEW mags, or ones that have new mag springs or ones that have +10% springs. Occurrences reduce over time. This means things are more fluid when mag springs are weaker.

    Solution: load up all new mags to full. Leave it loaded for days, or weeks. And the problem will subside. A weakened spring is still quite sufficient to push up all the rounds reliably.

    If you want it "now", Dremmel the area on the follower that come in contact with slide lock. That area is actually small, about as wide as the pencil tip. Grind it down just a bit.

    Happy shooting!

    Outdoor Hub mobile
     
  20. dsb1829

    dsb1829

    Messages:
    103
    Likes Received:
    0
    Joined:
    Nov 2, 2011
    Out of 5 mags that I own only 2 do not engage the slide lock with the slide removed and one rd in the mag. I am debating on taking the dremel to the other three and removing about .050-.100in off the flat. The only time I notice this issue is when I am shooting full power ammo. Maybe a stronger recoil spring would be a better solution to this than a permanent mod to the magazines. For now I will just use the 2 mags that have lesser engagement.

    FWIW, all 5 have the same follower.