Not Glocking so Glockily down the Glocky trail

My G20 quit feeding properly last summer, and I identified the problem as an original recoil spring that had gone soft.  A new Wolf spring and steel guide rod took care of that.  Then I wanted to try a new Lone Wolf barrel because I was getting so much case buldge that one use was about all I was comfortable with, and the LW barrels have more case support at the bottom under the case web area.  They also have standard cut rifling, which is supposed to better for cast lead bullets– something I’d like to try at some stage.


My first tryout of the new barrel led to a failure to feed the very first round, but after that it seemed to function normally and I figured all was well.  Not so fast.  Those were previously fired cases.  Last time out, with all new cases, I had several failures to feed, and had to bump the back of the slide to get it into battery.


This morning I tried feeding some rounds from several full magaxines, and here’s what happened;



Above is the slide resting quite securely, with its new, beefier recoil spring, on a jam.


Below, I’ve removed the magazine and locked the slide back.  That round is still wedged in the back of the chamber, and it took some fiinger pressure to dislodge it;



(Below) you see the mark below the case mouth, from the front of the feedramp digging into it;



My theory is that the new, softer cases are getting bitten more deeply than the work-hardened fired cases I tried the first time, resulting in more problems.  The original Glock barrel has much more “throating” or relief at the feed ramp area, which is why the Glock barrel is said to have less case support.  The LW barrel has more support in that area, but for now it doesn’t have enough clearance to feed reliably.  My new StarLine cases are trimmed at the factory to only a few thousandths over the minimum, and about 7 or 8 thousandths under the maximum case length.  The overall cart length is exactly, to within two or three thou extreme spread, what the Hornady manual (and several others) called for.  The rounds plunk right into the LW chamber with the barrel removed, but jam in the chamber when fed from any of several magazines, due to the feed angle and the tighter (actually just longer at the bottom because of less throating) chamber.


A longer bullet ogive might force the front of the cart down as it feeds, but at the moment I don’t know if that would help or hurt.  I might just put the perfectly good old barrel back in and live with super short case life for now.


I spent 30+ years doing custom work on various types of musical instruments, and long ago came up with an axiom I have repeated many, many times to perspective customers and fellow shop workers;  When you divert from the original design, expect a cascading series of unforseen problems.  In other words, expect to pay through the nose as we may have go back to the drawing board a time or two, to find ways to accommodate your custom thingamajig, making it work seamlessly with the rest of the system.


I noticed just yesterday that Brownell’s, I think it was, or maybe it was CTD, had a bunch of LW Glock barrels in a promotion, for all the Glock models except the 20, or those in 10mm.  This kind of sucks, because I was having a ball late in the summer shooting silhouettes at 100 yards.  The original barrel never seemed to give enough accuracy to make that a reasonable proposition.

12 thoughts on “Not Glocking so Glockily down the Glocky trail

  1. Lyle,

    First, does LW have any suggestions?

    If not, I would look at the breechface and extractor surfaces, and make sure they are smooth. Since you took away some slop in the “system”, everything else has to be in the best condition, because you are now making them more critical to its function. Anything that impedes the smooth (and fast) movement of the cartridge can now cause, or contribute, to a stoppage.

    I would try two things on the barrel breech. Using a Cratex rubber bit in a Fordom or Dremel, (or air die grinder) polish the top/roof of the chamber (stay away from the front shoulder of the chamber).

    Second, (and possibly most important) put a larger radius on the bottom edge (top of the feed ramp) of the chamber.

    You want to go slow with this. Do not use a hard cutter (stone or metal grinding/cutting bit). A soft tip will be safer. If you want to practice this, look for steel pipe in a reasonably close size, cut a fresh end, and give it a shot. The finer the grit, the slower it will remove metal, which is safer for your first try. Use a short bit, so you aren’t running the bit into the roof of the chamber. (Turning the roof into a washboard surface is VERY counterproductive!)

    You have two basic methods to consider here. One, is to just go for a particular radius. The other is to sneak up on it. This would require you to remove a little bit of metal, clean the barrel, reassemble everything, and see if they feed by dropping the slide. If so, go and shoot it to confirm it works dynamically. Otherwise, examine the brass, and go back and remove a bit more metal (larger radius). For comparison, the 1911 prints call out a 0.02″ radius for this edge. BTW, that is the size of a #60 drill bit (0.040″ diameter).

  2. My Ruger Mk. II had a similar failure mode, which was tracked down to a wobbly ejector! I’d looked at everything else, almost, before sending it off to Coal Creek’s gunsmithing shop in frustration.

  3. Are your magazine springs as old as the recoil spring? The new recoil spring might be trying to shove the rounds into the chamber before the mag can get them into position.

    If you’re bored you could also try playing with the depth your seating the bullets.

    My FNP-45 had the exact same failure mode as your glock – even outright denting some cases instead of just gouging them at the same spot as yours. I had been using the same XTP loads I’d been running in my sigs for years and the FN hated them. I lengthened the OAL on the same load by a few thousandths and it started working like a charm.

  4. IIRC, the Lone Wolf barrels are notorious for issues in the 10mm Glock, and ONLY in the 10mm Glocks.

    That screams “Dimensional issues!!!”, in that the LW barrels are slightly off in either external around the breech, or (far more likely) the chamber and/or feed ramp geometries.

  5. “When you divert from the original design, expect a cascading series of unforseen problems.”

    Welcome to my world of system engineering. And people wonder why we require a lot of expensive V&V testing when “it’s just a little change.” Yeah, just a little change till it affects something you didn’t anticipate…

  6. Hello Joe,

    That looks like an early model Glock 20, with the resulting pregnant guppyfish casings.

    There’s a blog posting floating around somewhere with a guy who had an older glock, put a newer Glock 10mm barrel in it, and it stopped the pregnant guppyfish issue… of course, then he stuck the old barrel back in to do some testing and blew up the gun.

    In any case, I have a newer model 20SF that doesn’t do the pregnant guppyfish. I’m wondering if you can just get a new replacement G20 barrel to see if that eliminates your concerns? I like Lone Wolf, and have several of their barrels for suppressor use, but I prefer the stock barrels for reliability.

    On a side note have you considered whether the steel guide rod is a good idea? I had a Glock mechanic tell me it wasn’t recommended because the recoil guide rod was supposed to be able to flex, and if it could not, it would put more strain on the frame of the gun. Just a thought, not sure if he’s right or not, but I put a new stock guide rod back in that gun and haven’t had any problems with it.

  7. Several good suggestions here. I’ve contacted LW and they say they’ll have an armorer contact me later. I asked said armorer to review this blog post first.

    Roberta x; My Mark II has the same problem with a perfectly tight and well adjusted ejector– It just won’t feed certain bullets. they’ll get bit at the chamber mouth, not altogether unlike what my LW Glock is doing, except the 22 bites the bullets rather than the cases. It hates the Remington “Gold” or whatever it’s called, but it feeds CCI plated and ArmsCore ammo just fine.

    One thing I haven’t done, which should be rather obvious, is to chamfer the outside of the case mouths and readjust the crimp die accordingly. Right now all I’ve done is take the new cases and size them in the RCBS carbide sizer, bell, load and crimp. A chamfer may make very little difference, but a very little difference may help a lot. So far I’ve merely adjusted the crimp die until the rounds plunk into the removed barrel with zero resistance.

    The obtuse angle representing the end of the feed ramp and the beginning of the chamber proper is very abrupt, i.e. “sharp” and so a very light polishing of that corner may make a big difference in avoiding the case-bite you see in the bottom photo.

    Lone Wolf says on their FAQs page that the Glock 10mms are notorious for bulging cases at the web, but we haven’t got to that point as these are new cases. And yes; I’ve gotten the pregnant guppy cases with the OEM barrel. Some of them have been scary in fact. I throw those away. Again though; this issue is not relevant when we’re only talking about the feeding of all-new ammo.

  8. I bought a box of Hornady XTP 180 gr defense loads, just to see what the Big Boys are doing different from my hand loads. Turns out; not much. They seat their bullets deeper (shorter COL) that what the Hornady loading manual calls for, by about 5 thou, and they’re less consistent in that department. They also crimp the snot out of them, such that their cases show a taper, downward, of 1 to 3 thou right at the case mouth, whereas I’ve been going for straight cylinder. Their cases are biting into the bullets. Case length is within a thou of mine. Theirs feed only slightly better, as I would have expected with the more severe crimp, but some of them still hung up on the LW barrel when dropping the slide from its lock, and every single one is getting bitten by the top (front) of the feed ramp.

    Yeah, so it’s the barrel.

  9. For what it’s worth, I have the same setup and it works well. I bought a barely used gen3 G20, and replace the recoil spring with a heavier one, and the barrel with a lone wolf. I reload 180 gr XTPs with starline brass, or whatever 10mm brass someone is stupid enough to leave behind. I have only had one failure with it, and it was a failure to eject, while shooting in 10 degree weather. I assume it was a lubrication/cold issue.

    I have experimented with working up several loads for this gun, using different bullets (150-200 grain, lead, FMJ, hollow-point, semi-waddcutter) and charges (subsonic to 1350 fps) and have never had a FTF.

    I assume that the pictures in your post was from hand-cycling the rounds through. If so, I can’t see how it would be attributable to an ejector/extractor that someone suggested above.

  10. Roger; You’re right– the extractor hasn’t come into play in any way yet in those photos, and the ejector isn’t interfering with the slide at all, but I can see where those things could happen. I’ve replaced my extractor twice now, and still every once in a great while there will be a fired case left behind in the chamber, resulting in a jam. That is a hand-fed round, dropped, as I said, from slide lock, by releasing the lock. The same jam will happen in live fire– case gets bitten on the sharp corner where the feed ramp meets the chamber. I also determined the other day that the bite occurs on the left side of the feed ramp, about 45 degrees up from the bottom.

    Still waiting to hear from LW. I’ll polish that corner lightly, using tripoli on a cottom buff in a Dermel if I don’t hear from them soon. Today I just got another e-mail saying I will be contacted.

  11. I had the exact same problems with the exact same components, and it was the Wolff recoil spring, not the LW barrel. Get the IMSI flat wound spring on the LW recoil rod, or get a Glock OEM spring, and you’ll be GTG.

  12. Lyle,
    a common miss-perception is the idea that the cartridge stays straight in line with the barrel as it goes through its feeding cycle. This is not the case. There are a number of variables that affect this. It can be doing a real dance, with the bullet or the base, or both, moving around. And, doing this at various points during the cycle. Generally, the less wobble there is, the better it works. It may be helpful to try to figure out why it is getting bit at that 45* angle. Look at the contact at the back end, as that may be steering the front (bullet) end. If you can find another 10mm, it might be useful to compare dimensions of the breechface and extractor.

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