Are Gen 4 G20 models still having FTF on last round?

General Firearms Handguns - Semi Auto
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ETA BLUF: Got some straight shooting, well-feeding ammo solutions in stock G20 for town and backcountry. Get some #4 followers if you don’t have them already. Most recent update on page 3. Thanks for the input!

Original Post:
Looking to pull the trigger on a G20 unless I can bring myself to wait for a G40. This is for backcountry use and will be running Buffalo Bore 220gr or similar Double Tap/Underwood/etc. after testing.

I’ve read in older threads here and elsewhere going back to SHOT 2013 demos through as recently as late 2014 that last round in the mag has a tendency to FTF, with slide locking back as though mag is dry. From reports, doesn’t matter if mag is loaded with 5 or 15 rounds, that hot loads lock back with last round still in the magazine.

Folks running mid- or lower-powered loads don’t seem to have an issue. Rather, folks running 200 grains or more. The high thumb excuse may or may not be at play in some cases, but considering that several were experienced with Gen 2 and/or Gen 3 G20 models, that is a suspicious blanket explanation.

Apparently Glock had replaced mags L and R with no effect, and typically stated that the models were fine. In several cases, Glock offered users a Gen 3 G20/G20SF in exchange for their Gen 4s after they persisted with complaints.

So, who has been running a Gen 4 G20 with 200 gr.+ loads and can give a good or bad report? Anyone work through the issue successfully? Sounds like 2013-2014 many chose to hunt down G20SFs rather than risk the Gen 4. By many accounts, the G20SF has been the line’s champ.

At $1-2/round, I don’t want to sign on to be quality control/problem solver for 1,000 rounds if this is a problem that one should inevitably expect. Again, it seems as though owners running lighter and standard loads did not encounter the issue, so it may not be an apparent issue unless one pushes the weapon.

Thanks for your thoughts.

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I have a G20 in both SF and Gen4 flavors. I have about 150 rounds of Hornady 200 grain XTP through the Gen4 and never had any FTF problems. Another 250-300 rounds of 180 FMJ and JHP have also been fired without issues.

BTW, the Gen4 feels a tad softer in the recoil department compared to the SF. I chalk that up to the recoil spring assembly.

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In my experience the factory Hornady 200 XTP has been reliable in Gen 3 and 4 20 and 29 models. Of course, it looks like Hornady just discontinued the 200 XTP, although they kept the 180 XTP.

The Trophy Bonded 180 seems to function in 20 and 29 models.

The Buffalo Bore and Corbon 200 penetrator loads do not function in multiple of my 20 models, and the 200 DT and Underwood are better but not 100 percent.

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Thanks for the feedback, both - especially with both of your experience with the two generations. I have no particular interest in Gen 4 features over the G20SF, so I’m all ears if anyone has a preference either way.

Sensei, do you know about when your Gen 4 was birthed?

Same to you, GJM, and can you describe the malfunctions you experienced with the hard cast rounds you’ve tried and if it was with both generations?

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The penetrator loads I refer to are FMJ, not hard cast.

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I have a gen 3 20sf, I routinely have the problem you are describing shooting 180gr underwood.

I read somewhere about filing the follower, I have not done it.

I have a bunch of mags, both std capacity, and 10 round, they are marked and there is no pattern, they have all done it. This is the only glock that has given me any trouble.

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Ah, sorry about that, GJM - I was assuming the Buffalo Bores, DTs, and Underwoods were hard cast.

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The plot thickens! I hadn’t read of Gen 3 G20SFs having the same issue until you mentioned it just now, so that is good to know. I guess it was a signals to noise issue that I only saw Gen 4 threads before, as a quick Google search just now revealed similar G20SF threads on multiple sites going back to 2011 that I missed. Based on yours and perhaps GJM’s experiences, as well as those threads, it’s not a Gen 4 G20 issue, but a broader G20/mag issue.

Perhaps that filing would help (or replacing #3 followers with #2 followers), but that sucks being forced to modify Glock mags that have always been so reliable on every other model. Of course, if it doesn’t work, it doesn’t work.

I wonder if a 22 or 24 pound recoil spring or Wolff mag springs would help at all? Some have suggested that is was more of a timing issue, thus the recoil spring, which BB has suggested replacing for the heavier bullets. Though, if it’s always the last round, it makes one wonder about the last round’s angle on the follower. It appears that spring replacements generally did not remedy this issue, though a few did not return to their threads after others suggested it…

I don’t mind experimenting a bit with ammo, followers, springs, or barrels for such a powerhouse on the platform, though it does start to get away from the functional appeal of most Glocks and certainly can be expensive with premium 10mm ammo, which seems to be the only ammo that induces the issues at hand. It also sounds generally like a hot mess of ‘upgrades.’ Perhaps I’ll just have to take my chances and if it will run for 14 rounds experiment more widely or treat is as a 14 round shooter with one loiterer in each mag.

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Mine was among the first models in the FDE frame - I bought it almost 2 years ago.

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I believe the issue is with 200 and 220 grain ammo driven fast, especially with flat point bullet shapes.

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The hornady 200 gr xtp works but it is like a 45 +p load

Been a while since I used a G20 gen 4 but I did use underwood hardcast 220 gr and their 200 gr xtp load. I may have experienced this phenomenon but I think it was an ammo problem. Underwood did a batch of ammo with nickel plated cases that were brittle. I was getting cracked cases and early slide locking. They replaced the ammo with regular brass and what I tried seemed to have worked fine but I also used the underwood stuff sparingly due to price so maybe there just wasn’t enough rounds put thru.

I would be tempted to just get the g40 for the velocity however the optics plate system means there is an eerily thin part of the slide, especially considering that it is a 10mm

That being said the g20 is one of my favorite handguns due to its versatility

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What great timing for this thread! I am also contemplating the purchase of a G20 Gen4, for backcountry use and will be using the heavies exclusively (Buffalo Bore 220gr or similar Double Tap/Underwood/etc.) I never knew of the problems with the entire G20 family (All Gens, SF, etc.) regarding hot and heavy loads.

To the OP, can you give a little more detail of the research you have uncovered? Is it correct that at least the chambered hot/heavy chambered round and the subsequent mag-fed hot/heavy rounds #1 thru #14 in the magazine will function reliably? If so, I may be able to live with that if I can get 15 rounds of TOTAL RELIABILITY before a reload.

Can you describe how bad the last round is jammed up? Is the last round half in the mag and half on the feed ramp, or is the last round fully seated in the mag, just that the slide is locked back? Is the last round causing the the slide to lock back WITHOUT the slide lock or is the slide lock somehow activating? If the mag can be ejected normally and cleanly, with the exception of one remaining round, and a fresh mag can be inserted and reloaded without further drama, I think I can live with 14+1 of 220gr goodness.

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not that bad, the slide locks back with one round remaining in the mag. not the end of the world, just irritating

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The slide stop is somehow activated into the up position into the slide stop notch?

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There’s an updated follower (4) for the 10mm Glocks. If you’re having issues, I’d contact their service dept.

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this is relevant to my interests…however, disappointing as well.

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I may have to call them, I have “2s” on my 10 rounders and “3s” on my std capacity mags, both are troubled.

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A couple of other G20 owners have recommended to me that if I shoot full-power 10mm loads such as the Underwood loads out of my G20, I should use a heavier-than-stock spring. They said they have no issues with 24-lb aftermarket recoil spring assemblies (RSAs) when shooting the full-power ammo.

So far I have only shot the mild stuff out of my bone-stock G20, with no issues. I ordered some Underwood 180gr FMJ and JHP ammo and a 24-lb RSA, and should have them in the mail soon. I’ll report back on my results.

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The Underwood ammo didn’t arrive yet, but the 24-lb recoil spring assembly did. I’m glad to report that the HPR 180gr FMJ (pretty mild, around 1100 fps I think) cycles 100% with the heavier recoil spring. Now to see how it works with the full-power Underwood.

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My blue label Gen4 G29 locks back with one in the mag, most frequently with the Pearce grip extensions (+0) on them. Does not seem to make a difference with ammo type. I called Glock today and they are sending me out the new followers. The followers that came with the pistol had the number 3 on them. Rep I talked to was real friendly and said they would get them right out to me. I will post an update when I get them in.