Quantcast
  1. Sign up now and join over 35,000 northwest gun owners. It's quick, easy, and 100% free!

Help! 10mm gun with .40 cal barrel

Discussion in 'General Firearm Discussion' started by rdt, Mar 5, 2010.

  1. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    my first gun, bought a couple years ago, a Tanfoglio Witness P, (im told this is a CZ clone?) with a composite frame. Bought a second mag for a .40 witness but it never fit right, engaged the mag release but could slip out. Closer inspection the new mag is slightly shorter (front to back) than the mag that came with the gun - and .40 rounds slip back and forth about 3/16 inch in the original mag. No play in the new mag. The barrel is marked .40 S&W. I recently learned .40 and 10mm differ only in length of the cartridge.

    so whats the deal? Is this really a 10mm gun i have been firing .40 through? Or is it just a b**tard? Can i fire 10mm through a .40 barrel? Or do i just have a bunch of mismatched gun parts to get rid of?
     
  2. Boats

    Boats Flicking A Switch To Open My Third Eye Well-Known Member

    Messages:
    470
    Likes Received:
    324
    If you bought it a couple of years ago, hadn't you fired it by now? If so, what did you fire from it?
     
  3. PhysicsGuy

    PhysicsGuy Corvallis, OR Resident Science Nut

    Messages:
    4,132
    Likes Received:
    155
    The cartridge stamped on the barrel is the cartridge that it is chambered in, so it appears that you have a .40. The newer witnesses only have one sized frame, so any magazine will fit in the frame. It just sounds like you had a 10mm magazine, which is not a big deal to use with .40 S&W. However is it NEVER safe to fire a dimensionally different cartridge when it is head spaced on the mouth (like all autoloader cartridges are), so you should never shoot .40 S&W in a 10mm pistol (however it is safe to fire in a 10mm revolver with moon clips because it headspaces on the rim that way)
     
  4. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    fired maybe 400 rounds of .40 S&W, two thirds factory reloads. seemed find except lots of failure to feed correctly/completely. all those unfired rounds spinning away as i racked again, well i chalked those up to being a novice: failure to keep tight control on the muzzle, ive heard .40 is considered a snappy round, composite body leaves it top heavy so it tends to spin - all robbing the recoil from the slide.

    local pistolsmith is who suggested the original mag is for 10mm.

    so options are...

    replace barrel/slide/etc with 10mm

    knuckle down and buy 10mm mags for a .40 S&W

    try to sell it as is

    part it out?
     
  5. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    headspaced? mouth?

    do you mean the breech (?) wont be fully closed?
     
  6. PhysicsGuy

    PhysicsGuy Corvallis, OR Resident Science Nut

    Messages:
    4,132
    Likes Received:
    155
    Headspace is the distance between the front and back of the cartridge, and is how the cartridge contacts the barrel when inserted. An autoloading (rimless) pistol cartridge usually is stopped on the mouth of the case when it is inserted in the barrel, and a rimmed cartridge, such as one for a revolver is held at the rim. When attempting to use a .40 S&W in something like a 10mm, the round will appear to chamber fine, but the case is not correctly supported or headspaced in this fashion, and is extremely unsafe. If it was the other way around, and a 10mm was inserted into a .40 S&W chamber, the round would headspace too shallow, and the gun would appear to be out of battery.

    Here is a wikipedia explanation;

    http://en.wikipedia.org/wiki/Headspace_(firearms)
     
  7. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    thanks for the explanation and the link!
     
  8. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    does anyone think its worth the trouble to change the barrel to a 10mm? or just buy 10mm mags, which seem harder to find, cause the .40 cal mags do not work.
     
  9. d1esel

    d1esel Ridgefield WA. Member

    Messages:
    231
    Likes Received:
    2
    Tanfoglio use to import large and small frames. They stopped importing the small frames many years ago. It sounds like you have a magazine for a small frame gun. Large frame mags measure 1.345” x 0.850”. Small frame mags are 1.250” x 0.800”.
     
  10. Lange22250

    Lange22250 Milwaukie Active Member

    Messages:
    349
    Likes Received:
    162
    You need to understand that Tanfoglio makes 2 different frame sizes. you have a large frame, so you need large frame .40 mags, which are probably identical to 10mm mags.
    The reason they do that is to increase magazine capacity. Tanfoglio makes a lot of pistols used in IPSC in Europe, where they are more popular than 1911's.
    Leave the pistol alone and get more large frame mags as long as you have no function issues with the mag that came with the gun. If you want a 10mm as well, you can get a 10mm barrel and it should be good to go.
    I use a large frame witness in 9mm and it's now my favorite.
    This guy did all the work on my pistol and he's a wealth of info and parts, as well as being a good guy and very helpful.
    http://www.henningshootsguns.com/index.html
     
  11. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    awesome. hennings site is cool. anyone out there want to buy a small frame witness mag?:paranoid:
     
  12. supergenius

    supergenius 206 Active Member

    Messages:
    592
    Likes Received:
    34
    double post
     
  13. supergenius

    supergenius 206 Active Member

    Messages:
    592
    Likes Received:
    34

    .40?


    Is this for a STEEL FRAME pistol? They are different for the poly.

    Post a couple pics please including one of the follower if you would. I have a .40 Baby Eagle (another CZ "clone" ) and just bought a 12 rounder... Id be interested in seeing it.... How many rounds of 40 does it hold?? Hopefully 12, and hopefully for a steel frame. Mine is a compact 40 with the 3.5" barrel.
    LMK.

    THX
     
  14. supergenius

    supergenius 206 Active Member

    Messages:
    592
    Likes Received:
    34
    iM INTERESTED
     
  15. greydog111

    greydog111 peoples repubilik of Oregon Active Member

    Messages:
    406
    Likes Received:
    80
    Dude! Have ya priced 10mm lately? Let alone try to find some! $35.00 for range pills. Yikes! Greydog.
     
  16. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    lets move this discussion about the magazine to the classifieds where it belongs, shall we?
     
  17. supergenius

    supergenius 206 Active Member

    Messages:
    592
    Likes Received:
    34
    You asked if anyone wanted to buy it... I do. How bout we take it to PM. LMK if its for a steel frame BE (may be marked AE41 at the bottom of the mag?) . If so (and it holds 12 plus), ill take it off your hands, would like to see a pic.

    Thank you.
     
  18. rdt

    rdt SW Portland Active Member

    Messages:
    407
    Likes Received:
    55
    yes, 12rds. i assume its for steel frame, the part number says "witness," not "witness p." MG-GT40-12, no other markings. Mec-Gar btw. working on pics. . . gotta run to work tho.
     
  19. supergenius

    supergenius 206 Active Member

    Messages:
    592
    Likes Received:
    34
    Ill take it, just LMK man.

    THX