Glock 20: The Ultimate 10mm and 40S&W Shooting Setup

For a long time I’ve been looking forward to producing a blog/video series covering 10mm Auto and 40 S&W. What’s not to like about taking 9mm to the next power level? 40 S&W essentially does that. Want to go extreme? 10mm Auto packs a major punch, it’s the most powerful semi auto handgun cartridge that can be considered “somewhat mainstream”. It’s been a while since I’ve loaded 10mm Auto- probably a good 10 years. So I thought this would be a great time to go deep on 10mm Auto and 40 S&W here on Ultimate Reloader! For years I’ve wanted to get my hands on a Glock 20, the full-size 10mm Auto pistol that pretty much sets the standard by which all others are measured by (10mm chambered 1911 pistol fans may beg to differ :)). What’s great about the Glock 20 is that you can get a “drop in” 40 S&W conversion barrel which essentially turns your Glock 20 into two pistols – one that shoots 10mm Auto, another that shoots 40 S&W- and the conversion process takes only about 15-20 seconds.

Glock 20 10mm pistol with Lone Wolf 40 S&W conversion barrel - Image copyright 2015 Ultimate Reloader
Glock 20 10mm pistol with Lone Wolf 40 S&W conversion barrel – Image copyright 2015 Ultimate Reloader

I missed out on a great deal on a used Glock 20 with conversion barrel about a year ago, so when I spotted an un-fired Glock 20 at my local gun shop, I bought it on the spot. Some people buy multiple guns chambered for the same cartridge so that reloading “overhead” can be kept to a minimum. My approach was the opposite: I want to experience and show as much reloading content as possible for each firearm I own. Such is life when you blog about reloading (and/or when reloading is your passion as it is for me).

The Glock 20 is a no-nonsense no-surprises consistent performer - Image Copyright 2015 Ultimate Reloader
The Glock 20 is a no-nonsense no-surprises consistent performer – Image Copyright 2015 Ultimate Reloader

Glocks are a matter of personal taste. People either like them, or don’t like them. Shooters will go on and on about the grip angle, the trigger, etc. To me they feel good, shoot good, are *very* easy to work on and take down, and I also appreciate the proliferation of aftermarket accessories. To put it simply: I’m a Glock fan. I don’t have a “Glock Perfection” bumper sticker on my truck, but I l like Glocks a lot.

Glock 20 Specs, from the Glock 20 product page:

  • Chambering: 10mm Auto
  • LENGTH: 209 mm / 8.22 in.
  • WIDTH: 32.50 mm / 1.27 in.
  • LENGTH BETWEEN SIGHTS: 172 mm / 6.77 in.
  • HEIGHT: 139 mm / 5.47 in.
  • BARREL HEIGHT: 32 mm / 1.26 in.
  • BARREL LENGTH: 117 mm / 4.60 in.

One of the aftermarket items I had my eye on was the very reasonably priced and high quality 40 S&W conversion barrels from Lone Wolf Distributors. Not only does this give your Glock 20 the ability to shoot 40 S&W ammunition, it also features a more “tight fitting” more fully supported chamber, and conventional rifling.

The Lone Wolf 2040N conversion barrel - Image Copyright 2015 Ultimate Reloader
The Lone Wolf 2040N conversion barrel – Image Copyright 2015 Ultimate Reloader

This barrel is CNC machined from 416R stainless steel forgings, and heat treated as well. The polished feed ramp helps a wide variety of ammunition feed reliably. Want to shoot hard cast lead bullets in your glock? The conventional rifling and high-quality machining make this no problem, in fact Lone Wolf states: “Ok to use lead, plated or jacketed bullets” on the official product page. Sounds good to me!

The machining on my Lone Wolf conversion barrel is top notch - Image copyright 2015 Ultimate Reloader
The machining on my Lone Wolf conversion barrel is top notch – Image copyright 2015 Ultimate Reloader

At just over $100 (I paid $114.) I feel this barrel is a great deal, and it definitely makes the Glock 20 more versatile. I also love the fact that while I may need to “de-bulge” range pickup brass, any rounds I shoot using this barrel will not suffer from “the Glock bulge” because of the more fully supported chamber in this barrel. That’s a plus for sure!

I’m looking forward to bringing you all some great stories about 10mm Auto and 40 S&W shooting and reloading. If you have specific things you’d like to see, or stories you’d like to share, please leave a comment!


31 thoughts on “Glock 20: The Ultimate 10mm and 40S&W Shooting Setup”

  1. The 10mm cartridge is a gas to shoot and reload. I owned a Glock 20, but the grip was just too large in diameter for me. When I shot the 20 it felt like I was trying to hang onto a telephone pole!

    1. Sounds like the opposite of what I feel shooting cowboy-style revolvers (I don’t have enough meat to hold on to!). I love the fat grip on Glocks because I have large hands. Good thing we have so many options. 🙂

      1. Gavin: I read all this, then went to Glock to see if they say it is OK (didn’t want to void my warranty). They replied that they DO NOT recommend any conversions except .40 cal to .357. That would mean they don’t recommend drop in .40 cal barrels in Glock 20s.

  2. I have a Glock 23 that is (was) a .40. I am pretty new at reloading and also wanted to cast bullets so I was concerned about the Glock and all the negatives that I heard about reloading. So, I bought a Lone Wolf .40 barrel and felt pretty comfortable reloading and shooting with the new barrel. Next I ordered a Lone Wolf 9mm barrel and now enjoy both 9 & 40 with the same firearm. I did have to change the extractor and now to switch I just change barrels. I wonder if 10mm would work in the G23?

    1. Dennis I also have a 23 and I bought a lone wolf 357 sig. barrel for it. It shoots great. I would like to know about the 10 also. I know that the 10 is a little over 1/2 inch longer.

        1. The 10mm cartridge is longer than the .40 (but less than 1/4in I think) so it would make sense that would not work in the .40 mags, which is what you would need to use in a G23.

          Going the other way, 10mm to .40 (or 357Sig) seems to work okay for most folks (including in my limited experience using a Lone Wolf .40 conversion bbl in a G29). In this case the mags are just a tad longer than the .40 needs but apparently there is enough tolerance it doesn’t cause any problems.

          The 10mm Glock and .45ACP receivers are the same size and the mags are interchangeable, and same with the 9mm, .40, and .357Sig receivers.

          1. But remember the extractor and ejector are different between the 9mm and .40/.357, and between 45ACP and 10mm, and for duty use these should agree with the caliber you’re using, to be safe.

        2. Unfortunately due to the longer overall length of the 10mm, it absolutely will not work with a G23. It requires a longer grip (front to back, not height) with longer magazine to fit the cartridges. That is the main reason why it shares platform with the 45 ACP.

  3. The 10mm is a great cartridge, I own 3 of them which happen to be all Glocks. When I hunt or fish the 10mm is by my side because of the amount of fire power the Glock 20 can dish out!!!

    1. Anyone aware of any real data regarding how full-power 10mm Auto will stand up to black bear? (I live in bear country, but no Grizzlies)

      1. Not sure on the data, but the pistols were issued Sledge Patron in Greenland as a defense against polar bears which the unit encounters during patrols. If the 10mm can handle a Polar bear, it can certainly handle a Grizzly/Black bear.

  4. Another aspect about the 10mm guns is conversion barrels like the 40S&W you already mentioned. How ever there is the 357Sig and 9x25Dillon conversions. There is even a 9mm conversion for the Glocks.

    The 10mm is a ballistically perfect cartridge with a wide range of bullet construction and weights to utilize the full potential form your very own pistols. Handloading allows one to tailor loads for specific needs and uses. Collecting the 10mm guns is addictive so be warned!

    I have handloaded for my 10mm guns since day one 1990 and developed my own loads when none existed using certain powders. The same for the 9x25Dillon which is another of my favorite cartridges!

    As I mentioned on the Facebook post many enthusiast hang out on the 10mmFirearms Forum where I am very active there sharing knowledge and documenting ammunition being sold commercially and others testing velocities and gelatin results. Be sure to check us out here;

    Best regards!

  5. Good logic. I bought a Wolf 9MM barrel for my G27 giving me both .40 S&W and 9MM in one gun. I was surprised at the accuracy, it tames recoil enough for my wife to shoot it comfortably and I can shoot any load/reloads with confidence.

    1. Bought two Glock 23s, .40. After several years, decided to reload. Find out factory barrel has what I call issues or design problems. No mention by Glock. I want a good “defender” for wife and I and only buy one kind of ammo. So now, to reload I have to buy a aftermarket barrel and maybe a bulge buster. Probably will due to the fact that people tell the the accuracy is improved. And recently I picked up a S&W, M&P, Shield, .40. Oh my God, this thing fits like a glove and is so well balanced it hardly feels like it is there. I have shot a .40 H&K. INSTANTLY, shot a better group than with my personal Glock. I had NEVER fired the H&K before. I would not say Glock is a bad gun, but it does lack a lot for me. And the reloading and barrel issue is kind of stinky. My impression is out of all the makers out there Glock belongs in the middle of the pack. I will keep mine, get a barrel, enjoy it, but no more Glocks for me.

  6. I went the opposite direction in a sense. I bought a 400 Corbon drop in barrel for my Glock 21.

    Now…considering how easy and cheap it is to get your hands on 45 ACP brass vs the cost of 10mm Auto brass…this conversion is logical. You’ve got to reload for either one so through Diamond K Brass…500 pieces of 45 ACP brass will run you $40.00….500 pieces of 10mm Auto brass is $150.00…with a Lee carbide 45 ACP sizer die…and who doesn’t have one of these!!…and a steel 400 Corbon Lee Precision sizer die…run the cases and you have 400 Corbon cases….case trim with a Lee Precision case length gauge and the deed is done. You do not have to lube the cases after sizing with the 45 ACP die then running the case into a 400 Corbon steel die. Cases come out bottle neck shaped and ready besides possible trimming.

    Look at the loading in the Hodgdon online reloading guide for 10mm Auto. Yes…you can get 357 Mag velocities using 155 grain 40 cal bullets…+ – 1,300 FPS….Hell of a bear stopper. However…I cast 170 grain Lee tumble lube bullets cast to the hard side and I’m pushing these bullets well over 1,200 FPS…per my chronograph. I see no signs of over pressure…no bullet push back using the Lee Factory Crimp die which is exceptionally easy to use. I intend to develop a load that will push these 170 hard cast bullets towards that 1,300 FPS velocity this summer.

    A Glock 21 conversion barrel to 400 Corbon through Lone Wolf will run $125.00 and is considered safe to use lead bullets since Lone Wolf does use stand groove and lands on their barrels plus the other benefits of a Lone Wolf barrel.

    Since the Glock 20 and the Glock 21’s are identical in size…in my view…the Glock 21 conversion offers ease of conversion…cost savings…brass availability by making your own with ease….and using the same magazines without feeding issues. Plus…yes…you can drop in other conversion barrels for the Glock 21 and you can even get a 45 ACP TO 10mm conversion barrel and another added barrel is a drop in 40 Super barrel. Now that 40 Super is something to experiment with according to ballistic charts…we shall see.

    It just can become overwhelming at times however trying to keep up with all the different loadings/calipers. My favorite conversion however is dropping in a 357 Sig barrels into my Glock 22’s.

    1. Thanks for the heads-up on 400 Corbon- looks very interesting! I may have to do a “400 Corbon drop-in barrel 1911” article with some case forming and reloaing coverage at some point in the future…

    2. While the G20 and G21 receivers are the same size, the G20’s slide is much heavier. Having seen a Glock’s aluminum slide stop block split in two on a G36 (probably due to a worn recoil spring), I have to wonder if a G21 10mm conversion might cause excessive beating of the gun (unless maybe there’s a new recoil spring that goes with it?).

      Also keep in mind that the extractor and ejector are different between the 9mm and .40/.357, and between 45ACP and 10mm, and for duty use these should agree with the caliber you’re using. Stay safe!

  7. 10mm. The perfect hunting semi auto round. I habeas shot multiple deer with it. They drop on the spot.

    As for loaded data. It’s pretty weak. Underwood pushes some good loads. But here is some of mine.

    155 gr xtp 1690

    180 gr xtp. 1475

    184 gr cast. 1610

    200gr mihec 1450.

    All those are with 800x. The 184 cast is over 1000ft lbs. In a semi auto.

    1. Just make sure the rounds are seated against the back of the mag tight. Give it a rap on your palm after loading and no problem. So far in the 4 years I have been using this set up I have only had problems if I didn’t “seat” the rounds toward the back… and those maybe amount to 4-5 misfeeds. Using the factory spring the action cycles perfectly everytime.

      Best part… the weight of the G20 absorbs a lot of the felt recoil of the .40SW rounds. It’s like shooting a light 9mm.

      1. My very point (Magazine Issue) about using a conversion barrel that uses like brass….Glock 22 over to 357 Sig…Glock 21 over to 400 Corbon….and even though I have to make my own 400 Corbon brass…357 Sig
        brass is so extremely affordable through Diamond K Brass why make your own 357 Sig brass using 40 S&W brass…only if you have too and that is exceptionally easy anyways.

        Then again..a few minutes spent changing over to any needed parts to accommodate a particular conversion is so minor it is a no issue situation…except….having to keep those swapping parts where you can find them if need be in a hurry….each to his own I suspect.

        My train of though is if I’m out and about training…I don’t have to have multiple magazines…just a barrel and ammo stored/carried in an entirely different case as you can imagine the consequences if a 357 Sig were chambered into a 40 S&W barrel….would the round even fire since the 357 Sig headspaces on the shoulder? Don’t think I’d like to find out.

        By the way…I’ve gotten my 357 Sig loads up to some real thumpers using 124 grain Lee truncated nose hard cast bullets…my own cast bullets of course using “Ample” linotype thrown in the melting pot.

  8. I bought a new Glock 29; installed a DPM recoil-reducing multi-guide Glock 29 spring; and later installed a Lone Wolf custom single port extended 10mm barrel. It made shooting standard load 10mm auto feel like a 40 S&W Glock 22, but while shooting a few 10 round mags of full-power Underwood 135 grain and 200 grain 10 mm rounds, there were at least one double-feed with each full magazine. Upon inspection of the brass, the full-power loads were bulging around the middle of the cases, as compared to the unchanged Winchester and standard-power 10mm reload casings. The Underwood ammo’s high pressure loadings caused brass to bulge long enough to be stuck in the chamber so that the extractor slipped and left a spent casing in the chamber, and caused the double feed. That is not good in a gunfight. Spent standard brass 10mm casings from Winchester and easily slid in and out of of the chamber of the gun after the leaving the range and before cleaning the barrel. Underwood spent shells had to be pushed in and out the chamber. Lone Wolf should either polish its barrels chambers, especially after black oxide treatment, or enlarge the chambers slightly into a cone shape. polishing after oxide treatment should be free to customers. My barrel still has some oxide coating in the chamber after shooting at least a 100 rounds of full-power 10mm ammo and 500 rounds of factor and reloaded standard ammo.

  9. Have onwed a G20 since Gen 1 back in 1992. Other than two kabooms (first one was a defective rear rail, Glock replace at no cost to me, the 2nd kaboom was my own darn fault, overcharged by 4.5g of Accurate #7 (I was a newb to reloading… painful lesson learned that day), felt that one for a week) never had a problem.

    Wanted to be able to get more practice and hone my marksmanship so I got a LoneWolf 10/40 conversion barrel 4 years ago. Love it! I can even have kids shoot it, although as with most folks and small hands the grip is a bit big for them. For me? Fits my paws perfectly.

    I am not one for looks but prefer reliable function and Glock delivers that for me. I also have a GCU while not a pistol, it’s still a hoot to shoot. Right now I have 4 G20’s. 2 Gen2 and 1 Gen 3 and a Gen 4. All my Glocks have Stormlake barrels in them. While the factory barrel works fine, the Glock smily for reloading is a pain and an extra step to add to the process. Plus the limitation of ammo you can shoot… I always tell my friends if they get Glocks to replace the factory barrels with aftermarket.

    Stormlake, LoneWolf both are excellent replacements. I use the Stormlake 6″ for hog hunting Bottom line… I wish the 10mm would go more main stream… be nice to see the ammo prices come down like .40SW. But until then, I guess I’ll just keep reloading my own!

  10. Hey Gavin, Why have you stopped making videos. I enjoyed them and looked forward to the information you gave us. Thanks, Hank

  11. Hello! I am about to buy a glock 20 but I was more interested in the 40 smith and wesson conversion barrel from LWD. I also heard the extractor needs to be replaced. What extractor is recommended?

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