Glock 17 gen4 Endurance Test: Week 28

1-Oct-11 – 14:53 by ToddG
38,676 rounds 8 stoppages
(+1 w/non-LCI extractor)
0 malfunctions 0 parts breakages

The reason you don’t see serious high round count tests in gun magazines is because over the course of many months and tens of thousands of rounds, stuff happens that can be hard to quantify.

This week, I received five new magazines to replace the original six that had begun showing signs of wear. As mentioned previously, my policy has always been to replace magazines rather than repair them. Once a part of the mag starts to show signs of wearing out, it’s not worth the risk to wait for other issues like spread feed lips, damaged followers, or broken floorplates to make a bad situation worse. So if a mag is no longer dependable enough to use for carry, it’s no longer worth keeping around.

Unfortunately, three of the five new magazines have a small problem. When I shoot, they eject from the gun of their own accord during recoil. As in, bang bang bang click. What the? Hey! Is that my mag on the floor? Yes it is, other Barry, yes it is.

Clearly, that sucks. And it’s all Glock’s fault so Glock sucks. Except… maybe not. See, when my good friend Todd Kennedy shot the gun using those magazines, they didn’t eject. When I shoot the gun strong hand only, they don’t eject. Only when I get my normal two handed grip do the mags run in fear. Clearly, my left hand is making contact with the mag catch — which is a slightly extended “FBI” mag catch — and putting just enough pressure on the catch to dislodge the mag in recoil.

So it’s my fault. Except… not exactly. All four of the mags I use for carry — two standard and two with factory +2 extenders — work fine and never self-eject. Two of the new mags don’t have the problem. All six of the old mags, now with new springs because rules be damned I need practice mags, work fine and don’t eject under recoil, either. pictured are the new (left) and worn (right) mag springs

So, it’s a big question mark. Are the mags sufficiently screwy that they’d be a problem in general, or is it just a bizarre incompatibility with yours truly? My plan is to have more people shoot the gun using those magazines as well as to test those magazines in another gen4 G17. If the problem extends beyond my one gun being shot by just me when using my particular 2-handed grip then I’ll count the mags as broken and they’ll be tallied above. If, on the other hand, it’s just some bad karma between me and these three particular magazines then I’ll eat the responsibility and not count it against the test gun.

In the meantime, I did actually shoot the gun quite a bit this week:

  • Turned in a 17-point-something clean run on the barrel/figure-8 drill during last weekends GetSOM class in Indianapolis… a personal best.
  • Took another run at the Half & Half drill (PTC version). Got all my hits at 20yd and 10yd but just could not break ten good shots from concealment in 2.5. My total score was another 280, with one miss and one late shot at 5yd. For giggles, I timed myself on a 10-shot run from concealment. Ten hits took 2.73 seconds with a 1.16 draw and splits from 0.15 to 0.18.
  • The dreaded 99 Drill beat me down yet again. After cleaning the first string (3 on 3×5 at 7yd in 2.5 seconds from concealment) and feeling generally awesome about myself, I dropped a whopping four points on each of the next two strings and then added insult to injury by dropping two out of nine at the 15yd line. Time to stick more pins in my JodyH voodoo doll.
  • Shot a fairly nice 4.80″ group at fifty yards standing offhand. This was with my carry ammo (Federal 124gr +p HST):


Also, passing the 37,500 mark meant it was time to replace the recoil spring assembly. The pistol will get the latest “0-2-4” spring installed the next time I’m at the range. As this week’s magazine problems demonstrate, it’s never smart to assume that a new part will work as well as the old part it’s replacing. Until I can put the new spring in the gun and fire a few hundred rounds downrange (including some of my carry ammo), I’ll stick with the old spring for day to day carry.

See you next week.

Train hard & stay safe! ToddG

Previous Glock 17 gen4 Endurance Test posts at

  1. 21 Responses to “Glock 17 gen4 Endurance Test: Week 28”

  2. I have a question for you. You mentioned the 124+P HST is your choice for carry. Have you tried the 147 +P HST? What do you think about each of them and why do you believe one is better than the other. I have both plus 124+P Gold Dot. Just looking for your opinion.

    By KD on Oct 1, 2011

  3. KD — All else being equal, I’m a fan of faster bullets. I’m not willing to compromise proven penetration & expansion for speed (which is why I don’t carry some of the crazy 115gr +p+ loads that tend to fragment and fail to penetrate) but if I am choosing between two rounds that have otherwise nearly identical jello results, I’m going with the faster one if I can control it well in recoil.

    My personal favorites are the 124gr +p HST, the 124gr +p Gold Dot (probably one of the most proven pistol rounds on the market thanks to NYPD), and the 127gr +p+ Ranger.

    By ToddG on Oct 1, 2011

  4. Could you post a few close up pictures of this gun?

    It’ would be greatly appreciated. I am following this closely.

    By Sam on Oct 1, 2011

  5. “What the? Hey! Is that my mag on the floor? Yes it is, other Barry, yes it is.”

    ROFL! 😀

    By Donovan on Oct 1, 2011

  6. Good stuff, especially the “it’s never smart to assume that a new part will work as well as the old part it’s replacing.”

    Words of wisdom right there.

    By Kirk in Utah on Oct 1, 2011

  7. I hope the two springs are from different capacity mags. Note the extra turn in the spring which otherwise appears identical.

    By John on Oct 1, 2011

  8. John — I ordered G17 mag springs. But good catch! FWIW, the new springs are working 100% in the original six practice mags.

    By ToddG on Oct 1, 2011

  9. Todd,

    Obviously your version of the VTAC Half & Half (pistol) is more difficult, but Kyle Lamb has slightly longer par times for the pistol version of this drill. He does 12, 6, and 3 seconds respectively. He also starts the drill from “position 3” or whatever your preferred high-ready is.

    By Nick Drakulich on Oct 2, 2011

  10. Crap! Disregard my last. I just saw that you already posted both versions of the half & half on the “drills” section.

    By Nick Drakulich on Oct 2, 2011

  11. I recall from the Armorer’s Course that when using the +2 extensions on the G17, the G22 (11 coil) spring is recommended. Was the spring with the extra coil from a factory 17 round magazine with the +2 installed?

    By JSGlock34 on Oct 2, 2011

  12. Did you just reference Archer? Why yes other Barry I think you did.

    By Jesse on Oct 3, 2011

  13. Jesse — Did I? Or did Archer reference me?

    By ToddG on Oct 3, 2011

  14. Are you secretly cyborg Barry? If so I’m sorry about your French fiance.

    By Jesse on Oct 4, 2011

  15. wait..are those both g17 mag springs? I see what means by the extra turn in the spring…confused.

    By dickmadison on Oct 4, 2011

  16. Umm, Todd, forgive me for perhaps belaboring the obvious-but what about simply removing the “FBI” magazine release and going back to the original OEM part…

    Best, Jon Stein

    By Jon Stein on Oct 4, 2011

  17. Jon — First, with my short fingers and the added girth from the Grip Force Adapter, the FBI catch works better. Second, there are enough FBI catches on gen4 guns in actual service that I find it hard to believe that’s the culprit. Third, I’ve been using the thing for about two months so unless it has “worn out” it doesn’t seem a likely cause.

    By ToddG on Oct 4, 2011

  18. Dick – the standard G17 magazine spring (SP00448 ) has 10 coils. When using the factory +2 extension (for a 19 round G17 magazine), Glock specifies use of the G22 magazine spring (SP02551 ), which has 11 coils.

    That is a *possible* explanation for the difference in the two springs pictured, as Todd mentioned that he has some magazines with the +2 extensions installed, but defer to Todd on the final word on that.

    By JSGlock34 on Oct 4, 2011

  19. Hmmm-If you’ve shot some 38K rounds without the problem, replace the magazines, and then a problem occurs, I’d think that the problem is caused by 1) flaws in the new components (in this case, the magazines), or 2) accumulated wear on other components (i.e., the “FBI” magazine release). While there certainly are enough of the “FBI” catches in service, I strongly suspect that very, very few, if any of the guns with them have anywhere close to your gun’s accumulated roundcount, so merely the fact that significant numbers of the component are in service is not necessarily of comparative statistical/problem-solving use here.

    Todd, I’d still recommend replacing the FBI release with the OEM part for awhile, and see if the problem persists. If it does, you’ve performed yeomanry service for users/potential useers of the FBI catch. If not, you’re a step further in isolating the true causal factor.

    Just you index better with “part B” does not mean that said part is ideal-it eeds to be examined in the total operational perspective. If it doesn’t adequately retain magazines, you merely have a single-shot gun that you can access the magazine release a bit easier than with the OEM component…

    Best, Jon Stein

    By Jon Stein on Oct 5, 2011

  20. JSGlock34 — The reality is that I was sent some replacement springs and installed them. It wasn’t until John pointed out the different number of coils that I even knew about it. Right now, the 11-coil springs are living in 17rd G17 magazines. I’m going to pick up some more for my +2 mags. Based on a discussion I had recently with a very squared away Glock armorer, there should be no downside to running the 11-coil in the G17 mags. And if it helps stave off the “slide over base” problems I was seeing, all the better.

    Jon — I see where you’re coming from and perhaps as time permits I’ll swap the old part back in. But I do know that there are a number of these catches that have been tested to high round counts without trouble. I am very suspicious that there could be some serious difference in design between the two when it comes to the material or dimensions of the actual contact point between mag & catch. But primarily, I simply lack the time over the next week or so to jump through that hoop. I’ve got some extra down time later this month and perhaps the swap test can happen then.

    By ToddG on Oct 5, 2011

  21. Todd, another possibility to consider is that there might be a slight dimensional irregularity in the magazine tubes (or just in the magazine catch niche area) of the new magazines-perhaps some shrinkage of the polymer during the curing/cooling process after they were molded…shades of the E-Serial rear receiver rail issues of years ago…

    Best, Jon Stein

    By Jon Stein on Oct 5, 2011

  22. I recently ran into a similiar issue with my Gen 4 Glock 17 when I replaced the OEM mag catch with an extended aluminum catch from Glockstore. The magazine consistently ejected after firing only one round.

    I isoloated the magazines by running them through my buddies Glock and it had no issues. I cursed through the day because I didn’t have the foresight to bring the OEM parts out with me, but you live and learn.

    Haven’t had a chance to try the OEM again…but I don’t suspect any issues…hopefully.

    By Henry Wong on Jan 10, 2012

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