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G21 Gen 4 10mm Conversion - Anyone?

Discussion in 'General Glocking' started by Winston.Smith, Sep 28, 2011.

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  1. Winston.Smith

    Winston.Smith Dismembered

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    Has anyone tried a KKM (or similar) conversion barrel to 10mm in a new G21 Generation 4?

    What's the reliability (since LWD claims 10% FTE/FTF on their barrels so they stopped selling them)?
     
  2. Winston.Smith

    Winston.Smith Dismembered

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  3. 21Carrier

    21Carrier Until I Gota 29

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    I know reliability was supposed to be good with the Gen3s and KKM barrels. Did LWD stop making the G21 barrel, too? I thought they just stopped selling the G30 version. Anyway, I'd assume the KKM barrel would work fine in a Gen4 G21. Only way is to try it.
     
  4. Remington4Life

    Remington4Life

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    you have to change to extractor to a g20 one
     
  5. Gtoboi65

    Gtoboi65

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    sorry to bring back an old thread but where would you find an extractor for the g20 that would work with the fourth generation glocks? I'm new to all of this and am very interested.
     
  6. GRT45

    GRT45 Transform & Win

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    While I'm very familiar with the conversion of the Gen3 G21 45ACP to 10mm, the conversion for the Gen4 G21 is relatively new territory.

    I recommend that you first contact Kevin McIntire at KKM Precision, Inc. (775-246-5444) as a trusted resource for the latest thinking on converting the Gen4 G21. If you don't want to phone them, a request using the contact form at KKM will probably make its way to Kevin.

    For one thing, the conversion of the Gen3 G21 to 10mm does not necessarily require an extractor from a 10mm Glock. KKM suggests some minor gunsmith work on the stock .45 extractor that enables it to function reliably for 10mm and 45ACP. This modification is an option for the extractor in the Gen4 G21 also.

    One of the challenges I see, at present, in converting the Gen4 G21 is there are precious few options to increase the recoil spring strength of the new dual recoil spring to something greater than stock 17 lbs. Many shooters want a heavier spring weight to accommodate the full-power 10mm ammo loads, and this is especially important for the G21 conversion (slightly lighter slide than G20). The only option right now is probably a Gen4 Conversion Recoil Insert that will allow one to use a heavier Gen3 single recoil spring. IMHO, it's not an attractive option to be forced to give up the dual recoil spring in the Gen4 G21. If the stock 17-lb dual recoil spring in the Gen4 G21 works for the 10mm ammo you prefer and doesn't throw brass more than 10 feet, it's probably wise to stick with the OEM Gen4 RSA.

    My hope is that DPM Systems will offer a mechanical recoil reduction system RSA for the Gen4 G21 in the near future. I have contacted DPM to inquire about the expected release date for the unit. I think a DPM RSA would be an elegant solution.
     
    Last edited: May 30, 2012
  7. Gtoboi65

    Gtoboi65

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    Thank you very much for taking your time to address these issues for me. I also agree that the gen3 recoil spring insert is not an option. I suppose the wait is still out for the gen 4 20.
     
  8. GRT45

    GRT45 Transform & Win

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    You're welcome and I want to add an update for your original question about which Gen3 10mm extractor will fit the Gen4 G21 for a 10mm conversion.

    I confirmed with Glock, Inc. that the .45ACP extractor in the G21 Gen4 is the same part number used in the Gen3 21/21SF (Part No. SP01902).

    Since the Gen3 10mm extractor can replace the .45 extractor of a converted Gen3 G21, it will also fit the converted Gen4 G21. The part number of the Gen3 10mm LCI extractor is SP01909.

    To expand on what I posted above, try using the stock .45 extractor first in the converted pistol because many find that works perfectly fine. If it doesn't operate reliably with a stock .45 extractor, the KKM recommendation to modify the stock .45 extractor rather than replace it with a 10mm extractor also applies to the Gen4 G21 extractor since the part is identical for Gen 3 & 4.
     
    Last edited: Apr 1, 2012
  9. HK Dan

    HK Dan

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    I didn't have any of those issues with my Gen III conversion, G21SF to 10mm. It worked fine with a barrel swap and a new mag.
     
  10. GRT45

    GRT45 Transform & Win

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    HK Dan, your experience with a trouble-free conversion of the Gen3 G21/21SF to 10mm has been shared by many.

    COSteve has an excellent post with closeup photos at AR15.com that goes into the reasons some have issues with the extractor while others have no problems with the stock .45 extractor. COSteve developed the G21 45-10mm conversion barrel with Kevin McIntire at KKM in 2005. He writes the following:
    COSteve: "As to what parts are really needed to switch calibers, yes it's true, one only needs to switch barrels and magazines to change the calibers. That said, there have been some people who have had extraction issues with the conversion barrel in their stock Glock slide. Not all have an issue but some do. My guess is that it's a question of tolerances between the breachface and extractor. Slides on the tighter side don't exhibit the issue but one's on the looser side may."
    Read his post at the link above (time stamped 12/4/2009 5:15:58 PM) where he goes into much greater detail.

    KKM now suggests some minor gunsmith work on the stock .45 extractor that enables it to function more reliably for 10mm and continue to work for 45ACP. It involves removing 0.020" from the 'pad' on the inside of the .45 LCI extractor allowing it to travel closer to the axis of the bore and make solid contact with the 10mm case. It certainly doesn't require a custom slide with tighter tolerances that COSteve mentions in his 12/4/2009 post.
     
    Last edited: May 30, 2012
  11. DFin

    DFin

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    What tools do you use to file the pad down?
     
  12. sgtlmj

    sgtlmj NRA Life Member Millennium Member

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    I ran a KKM in my Gen4 G21 with the stock 45 extractor without any issues.
     
  13. GRT45

    GRT45 Transform & Win

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    To anybody considering this .45 extractor modification, I strongly suggest that you first speak with Kevin at KKM Precision, Inc. That said, my thoughts about tools required are a small needle file with a flat face and a digital caliper or a micrometer.
     
    Last edited: Jul 6, 2012
  14. hkcavalier

    hkcavalier

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    I am planning on doing this conversion to my recently acquired G21 Gen4. Purpose is to make a "woods" gun that's weather-resistant and throws 15+1 projectiles in the .41 magnum class at any critter. I live in WA so bears and cougars are the main threat. As I plan on using 200+ grain heavy LFN loads (like Buffalo Bore or Double Tap) vs. the more .40 S&W spec 135gr defensive stuff I am pretty sure the 17lb spring is a no-go.

    So, summing up what I've seen in the thread, I would:

    1. Get a barrel from KKM or Storm Lake
    2. Get a recoil assembly adapter ring
    3. Get a 22lb Gen3 spring assembly
    4. Get G20 magazines
    5. Go shooting with some 10mm and see what happens
    6. If you have extraction issues, swap extractors or do the file method described here (very slowly and carefully with an accurate caliper to verify).
     
  15. GRT45

    GRT45 Transform & Win

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    That summarizes it pretty well, but there is new information to pass along regarding Items 2 & 3 in your checklist. Contact BT Guide Rods (Bill Freeburn at 412-542-8189) and ask about a captured, dual recoil spring with stainless steel guide rod for the Gen4 G21 they have tested and are making available immediately. It's not on their website yet. My understanding is it can be customized with different ISMI springs to suit your requirements. A tool kit is available that makes changing the springs quick and easy.

    I also received email from DPM Systems informing me the mechanical recoil reduction system RSA for the Gen4 G21 would be available in May, but I haven't seen any evidence of that on their website as of now.
     
    Last edited: Jun 3, 2012
  16. hkcavalier

    hkcavalier

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    Thanks for the additional info! I'll have to check out the BT product, I shouldn't need it until mid July so there is some slack time.
     
  17. WarEagle32

    WarEagle32

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    Love to give my 30 a 10mm try!
     
  18. myglocksrock

    myglocksrock

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    I dont have the g20 or 21, i want to buy one of them, which one is easier less hassle to convert g20 to .45 or g21 to 10mm i will be buying gen 4
     
    Last edited: Jul 6, 2012
  19. hkcavalier

    hkcavalier

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    Can't convert a G20 to .45ACP. You'd need a G21 slide and barrel.
     
  20. boris96

    boris96

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    I have a gen2 g22, can I convert it to 10mm? A g20 barrel? Thanks