Who's the #@%&* who told me I could shoot .40s&w out of my 10mm bbl?

Discussion in 'The 10 Ring' started by G29SFWTF, Sep 18, 2012.

  1. LOL Opie1 I must have too much time on my hands to think this stuff up. :supergrin:

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  2. don't worry, soon will see "my extractor broke" :rofl:

  3. I understand that 10mm costs a lot more than 40SW, but if you are only going to shoot 40SW out of a 10mm Glock, why not just buy a 22/23/27?
  4. Speaking for myself I'm not going to shoot .40 exclusively. But until I get around to being a reloader, this gives me a lot more shooting time with this g29 than I otherwise would have. I bought the gun used with a bunch of bells and whistles and I've added a few things too and now I just like shooting it.
  5. A quick thought experiment tells me that the extractor is the only thing holding the cartridge against the breech face.

    But if it works, do it.
  6. Not hardly.

    But, if that's what you believe, precede. The extractor was never designed to hold the case against the breach face although shooting the short cases takes advantage of the extractor to breach dimension relationship. Possibly the manufacturer should just eliminate the final machining of the shoulder in the chamber altogether under the premise that it is unnecessary. I mean, there is no need to regulate case length and the COAL length could be limited by the rifling in the leade.

    When I see Glock (or any other manufacturer for that matter) say that it is acceptable to shoot ammunition in any gun for which the gun is not chambered, I'll buy into it. Until then, this is a totally false economy and any body who does this is totally on their own if something bad happens.

    Oh, incidentally, the "no reloads" argument doesn't hold any water because the reason for it is totally different.
  7. dm1906

    dm1906 Retired SO

    Really? Get out your sliderule....

    The 10mm CASE length tolerance is MUCH less than what the extractor allows. You cannot chamber a case, within tolerance, and have it forward of the extractor. Therefor, it is behind the extractor, with a space between the case mouth and end of the chamber. If the case fully engaged the chamber, every time, the case head would be spaced away from the breach, every time. This has no relevance to what we are discussing.

    If your cases are fully engaging the chamber and the breach, the cases are too long, and out of spec. This has nothing to do with the lede/throat.

    If the case head is forward of the extractor, it won't fire. If your pistol fires, the case head is being held, by spring tension, firmly against the breach. If it isn't, your gun is broken, or you've chambered a round other than a 10mm.

    Whether or not the extractor was ever designed to do this, isn't relevant. It does it, by design or otherwise.
  8. I have no dog in this fight, but the time I checked the extractor had .030" slop, which let the case mouth be what set headspace between the min and trim to length.
  9. I haven't checked this dimension to verify it but development of the "trim to length" has zero to do with the design process which determined the breach face to extractor hook length. dm1906 would argue that the tolerances left in order for the extractor to function properly and for ammunition to feed from the magazine to chamber reliably make the shoulder in the chamber irrelevant. Actually, the shoulder is machined the way it is to limit forward motion of the case during the firing sequence. The extractor was not designed for this purpose. Although a byproduct of it's method of operation and may provide some benefit in this area, the intended mechanics of the operation of the pistol does not include the use of the extractor for this. That being the case the manufacturer never designed the extractor with that in mind. dm1906 would propose that there is no minimum case length specification at all as long as favorable dimensional relationships between the extractor hook, case extractor groove and rim and breach face are maintained. The chamber's shoulder is of no particular significance and could and probably should be deleted as obsolete.

    I am not of that particular persuasion and must therefore just agree to disagree.
    #49 BruceO, Sep 26, 2012
    Last edited: Sep 26, 2012
  10. I have tried the experiment and had no issues - maybe I was lucky. Better question is does anyone have any documented proof of a G20 blown up by using 40S&W? I can see beating up the extractor but that is easy enough to change. There appear to be a lot of guys trying this - curious if anyone has really had a bad experience.
  11. You also erode the shoulder in the chamber, among other things. The only bad things are not just the possibility of a catastrophic failure although that may be sole concern of some.

    #51 BruceO, Sep 26, 2012
    Last edited: Sep 26, 2012
  12. dm1906

    dm1906 Retired SO

    Erosion is no more likely than with any other cartridge, correct or not. And the article does not refer to Glock pistols. We've repeated, over and over again, this should not be tried in any other brand pistol. I'm NOT trying to convince anyone to try anything they are not absolutely comfortable with, or that may be unsafe. Only trying to dispel myth and rumor regarding THIS situation. The Glock doesn't know the difference, nor does it care. A .40 round won't fire (any more likely than if it were a 10mm round) if it's isn't properly chambered (either would be equally bad). Other pistols, such as those in the article, may. If the Glock does, it was already broken, or modified in such a way this should never be attempted (such as an extended striker, which is a bad mod, in almost any case).
  13. Yah, right.

    It doesn't mention the Glock by name because it's a general statement.

  14. It's funny how some people will argue against doing this, despite all logical explanations, without having a clue what they're talking about. If you don't understand why this can be done in a Glock but shouldn't be done in other pistols, fine, but quit acting like you're smarter than the rest of us - you aren't. Open your mind and look at the facts, and quit going off old rumors.

    Throat and chamber erosion is no different firing 40 vs 10mm - it's practically non-existent with either round; these aren't magnum rifle rounds with large powder volumes and small bores.
  15. Javelin

    Javelin Got Glock?
    Silver Member

    Yeah because that extra 3mm of brass on the 10mm casing and barrel chamber is just there for aesthetics anyway......
  16. dm1906

    dm1906 Retired SO

    Right. It is/was a general statement, general to the pistols examined, which didn't include Glock. The reasons for the failures they describe are not characteristic of the function of a Glock pistol. I/we do not recommend this practice in pistols other than Glock for the reasons they describe. Please provide a source describing a Glock failure, under these conditions. If it's happened, it's a big secret.

  17. Well I know a lot of folks like drama but both rounds are similiar CUP pressure with the 10mm being a bit higher.

    So it's not likely you're gonna get some catastrophic failure that causes the pistol to blow-up like a pipe-bomb by using a shorter lower pressure round.

    At most you'll damage the extractor, or the round will slip past the extractor and fail to fire.
  18. Someone make a YouTube video about this maybe moss pawnshop channel will do a special I do know you can buy caliber inserts for a 12 Gauge and shoot 9mm 22lr 357 out of it safely but I can't comment on the accuracy but if it comes down to you finding assorted ammo and only a shot gun these inserts would be a heaven send in a crisis.
  19. Cool thread.

    Maybe reason enough to buy a 10mm now :)
  20. vaquero aleman

    vaquero aleman "ah-lay-mahn"

    I'll up your ante,

    I have a G21, in which I placed a factory G20 6" barrel, and fired some 40 S&W. I use a Wolff guide rod with #20 spring. I shot Underwood 165gr 40 for a few rounds and then tried some Underwood 135gr 40. I threw away the first three rounds, of the 135gr, because they did not ignite. The pin had obviously punched the primer but did not ignite it. The 165gr fired without incident but the 135gr would not fire and I can only assume it was because the extractor could not hold the case against the breech solidly enough. Therefore, I intend to get a 10 to 40 conversion barrel to use in my G21. And I did perform the "KKM" mod to the extractor.

    And, I must add, that there is no "why" only "just because".





    #60 vaquero aleman, Jan 19, 2013
    Last edited: Jan 23, 2013

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