How To Convert Your Glock From 40 To 9mm Safely

Did you know that you can convert your Glock from 40 to 9mm quickly and safely?

Converting your Glock from .40 or .357 Sig to 9mm can be a super easy affair or a rather complicated one depending on what method you use to complete the conversion. In this episode of TFB TV, Patrick shows you two methods for converting your gun the proper way. Follow along step by step with a certified Glock armorer and do things the right way with factory Glock parts or use a Lone Wolf conversion barrel and save a ton of money and quite a lot of time.

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Transcript ….
[coming soon]


  • Scott Tuttle

    once you get to ‘replace barrel with cheaper, easier lone wolf barrel and call it a day’ the only reason to keep watching is morbid curiosity 😛

    • FOC Ewe

      It’s like they’re reviewing Forum Stickies for something to write about between sponsor plugs.

  • Madison J Coleman

    With the mass amount of trade in Glock 40’s and the mass amount of newbs out running around, this entire video was like a much needed PSA for how to NOT kaboom your Glock because you read something dumb on the internet like “just put a G19 barrel in the G23 slide and go!”.

  • Anonymoose

    I thought he was going to just throw his G23 away and whip out a G19.

  • Phillip Shen

    With the 40-9mm barrel change, I would actually suggest getting a lighter recoil spring as well. Otherwise the gun may not cycle unless you shoot hotter 9mm loads.

    • SpringTimeInWinter

      I would argue that you’d be fine with the same spring assuming you are shooting SAAMI spec (or hotter) 9mm loads; it’s shooting under-powered 9mm loads that will get you into trouble. There are more than a few out there.

      Factory Glock recoil springs for both the 19 and 23 are 18#s each (in Gen 3). Same factory part number (SP02457). The 26/27 are the same too (in both Gen3 and Gen4), part number SP02211. The Gen4 Glock 19 spring was tuned to accept a broader range of ammo, which isn’t the issue in .40’s due to them all being far closer in pressures (not as broad of a power band as 9mm). This “changing to lighter recoil spring for 9mm in my converted Glock” is a fallacy that needs to stop being perpetuated, and you can wind up battering your slide more with 9mm and your underpowered spring than in your .40 w/ std spring. Just don’t shoot under-powered ammo and you’re good to go with the .40 spring.

      • FOC Ewe

        My G24 with a KKM 9mm conversion barrel does not like weak/dirty or most bulk 9mm ball.

    • Badwolf

      Just 40-9 barrel and 9mm mag is fine as shown in Patrick’s video.

      And for me too so far, with more than thousand rounds and all kinds of ammo.

    • Patrick R. – Senior Writer

      You understand the Gen 3 recoil springs are the same between 9 and 40 right?

      • Phillip Shen

        Didn’t know I’d get so much flak for such a small recommendation.

        This was based on my personal (albeit anecdotal for you guys) experience. The caveat is that I am a reloader. I’ve developed a load for 9mm that works with all my other 9mms — 92FS, CZ75, SP01, CZ Rami — but lo and behold it was jam o’matic with conversion barrel + original spring. Upon reading other people’s experiences (therefore also giving you guys a hint, this is not something only I experienced), I decided to go with a slightly lighter recoil srping (13lb) from Lone Wolf, and guess what? All cycling problems went away.

        Are my loads slightly lighter than normal? Hard to say, I’m loading at the higher end of what’s acceptable for a 115 gr plated round with Universal, but considering it’s had no issues with this load with my other 9’s, for my own instance I considered the Glock 22 spring perhaps too tight for my setup.

        So hence, just a recommendation guys! And remember, I did caveat too that it may not work for lighter loads =).

  • Hoth

    Throw the POS in the garbage and buy a good 9mm?

    • John Wimper

      POS??? Really. Not in my experience of many thousands of rounds of all types of 9mm ammo in a converted Gen 3 G22 that I paid $285 for ….has been everything but a “POS” been the most reliable, accurate pistol I own.

  • Noishkel

    That’s easy. You sell your Glock, and buy a Sig.

    But hey, member… your Glock you keep needing to buy new parts for is still ‘perfection’.

    • Dakota Raduenz

      Two Sigs, one Glock. But then, the Glock cost half what the cheaper, used Sig did…

  • thedonn007

    I just have the conversion barrel for my glock 22. Is there anything else I need to change to make it 100%

    • DrewN

      I changed the extractor as well on mine. Recommended and cheap, plus you can lose/gain the LCI if it bugs you. That’s all I did and I have 20 something K rounds thru it.

      • thedonn007

        Thanks. I thought I had read that somewhere. From Patricks video, sounds like I do not want to change the ejector. Having the LCI does not bug me.

    • I believe the extractor and ejector are different for 9 vs. 40.

    • Patrick R. – Senior Writer

      No. It needs no other parts than a barrel and mag.

  • Keiichi

    Seems like it defeats the purpose…

    I’ll keep mine as is, thanks.

    • ironked

      I bought mine when ammo supply was sort of squirrelly. Having the ability to use both calibers meant I could buy what I could find.

  • ironked

    A 23 was my first pistol. I was pretty ignorant at the time. I liked the way it felt, and was sold on converting to 9. Bought the gun, a Lone Wolf conversion barrel and half a dozen 19/17 mags. Hasn’t been a problem.

  • gordon

    Why buy a 10mm if you want a 9mm? Why not just buy a 9mm to begin with??

    • nate

      good question, only reason I can think of is that you get a police trade in .40 cal for dirt dirt cheap. but even then buying a barrel, and a new ejector and new magazines quickly adds up making a conversation not worth it

      • John Wimper

        True, but, you can essentially have 2 guns in one,.

  • Saint Stephen the Obvious

    Got a glock 23 and put about 1,000 .40 rounds through it. Then got a 9mm barrel from lone wolf, some 9mm mags and over 7,500 rounds or so later, still no problems. Also got the .357 sig barrel and a couple of mags – only put about 500 rounds through it but still no problems.

    The Lord works in mysterious ways.


  • John Wimper

    I have thousands of rounds through a converted G22, no probelmos at all, even ran it 1000 rounds with no cleaning as a torture test…..not a single problem. I actually prefer it over my G17 as the heavier barell weight is very pleasing regarding recoil.

    Highly recommended to get a LEO trade in G22, get a conversion barrel, and if you really want a true conversion, get a G17 extractor, ejector, and spring cups and some G17 mags and you are good to go.

    • Patrick R. – Senior Writer

      No. Do not use a conversion barrel with 9mm parts. They are designed to use the .40 parts.

      • John Wimper

        OK, thanks. I thought I would have bad ejection using .40 ejector due to hitting casing farther out due to larger diameter location than the smaller diameter 9mm.

        • Michael

          With my gen 2 g23 and lone wolf conversion barrel I had to replace the ejector to get function. May depend on what barrel you get but I’ve had to do it on g22 and g23. They don’t contact the primer on mine.

        • Patrick R. – Senior Writer

          Nope, they take that in to account.

  • iksnilol

    Should’a been titled: “How to make a handgun outta a grenade”

  • 22winmag

    Simple caliber conversion: Take your .40S&W Glocktastic pearshooter to the pawn shop to raise funds for an FNS-9.