Extractor screw

Discussion in 'P-3AT' started by sgunsel, Nov 5, 2007.

  1. sgunsel

    sgunsel New Member

    9
    Oct 16, 2005
    I'd like to replace the rounded socket (from factory) extractor screw on my P3AT. I searched the archives, but can't seem to find the proper length of the 6-32 button head screw. I know I can get one from KelTec, but prefer to buy a known "good" part. The material specs on 6-32 button head screws vary tremendously depending on material and manufacturer. I know a better screw could strip the frame if overtightened, but prefer to not have a rounded socket.

    Thanks.

    sgunsel
     
  2. adamsesq

    adamsesq New Member

    Dec 25, 2006
    Why not pull it out and measure it? :-/

    -Scott
     

  3. kaltectom

    kaltectom New Member

    702
    Jun 4, 2005
    You might want to read this from the TecWorks section of this forum....this "screw" also affects the firing pin

    http://www.ktog.org/firingpin.htm

    There are some posts where people have acquired substitutes. I stripped the head on mine a couple of years ago. Keltec had one, in the mail, to me the next day. I did not pay attention and used loctite on the screw without orienting the firing pin. I ended up having to get a new slide, firing pin and etc.
    Of course KelTec did all this under their great warranty program. I don't think I'd use anything but the Keltec parts.
     
  4. How did it get rounded in the first place?

    When I get a new 3AT I throw the enclosed allen wrench away. The KT Supplied wrenches seem to cause more trouble than they can fix.

    You may want to consider getting a new screw from KT and going to a tool store and buying a high quality wrench.
     
  5. Bobo

    Bobo Active Member Supporter

    Jun 13, 2005
    The Kel-Tec button heads screws are not a standard length. I did as shown below until Kel-Tec came out with their new, harder version. Then I ordered a couple of those.


    I made one with a standard, steel, 6-32, pan-head, screw and an internal-tooth lock washer. I had these items in my used hardware stash, but they can be acquired at any hardware store or home improvement center.
    I have fired many hundreds of rounds with this without it loosening or any other problems (no Loktite needed).

    CAUTION: Because the button head screw also retains the firing pin and spring; before removing the old button head screw:
    1. Remove the magazine.
    2. Make sure the gun is unloaded.
    3. If you have one, put a snap cap in the magazine and load it. If you don’t have a snap cap it’s OK, just better to use one if you have it.
    4. Remove the magazine.
    5. Pull the trigger so the hammer goes down against the firing pin.
    6. Leave the gun fully assembled, i.e. don’t remove the slide.
    7. Now it’s OK to remove the button head screw.

    Start with a steel, 6-32 x 3/8" pan-head screw and a 6-32 internal-tooth lock washer (and three 6-32 nuts, not shown).
    Original Kel-Tec screw shown on the right.
    [​IMG]

    Put the three 6-32 nuts on the screw which makes the thread length equal to the original screw (including the lock washer).
    [​IMG]

    File the screw threads down, flush with the top nut.
    [​IMG]

    As the nuts are removed they help realign and smooth the threads that the filing roughed up.
    [​IMG]

    That's it!
    It looks ugly - but works great! The slotted head is also a great loosening indicator, although it never has loosened.
    [​IMG]

    Just for looks, after Kel-Tec came out with the newer, harder version of the screw I replaced the above with one of those and bit of Loktite.
     
  6. JFB

    JFB New Member

    Jul 25, 2005
    I just took 4 out of the bags from KT and measured just the threads
    1)- 0.235"
    2)- 0.250"
    3)- 0.270"
    4)- 0.275"


    :-/
     
  7. adamsesq

    adamsesq New Member

    Dec 25, 2006
    I knew when I saw that the last post was from JFB that we would have answers, and then some!  Gotta love those engineers!!

    Just hijacking this thread a bit - let me ask you JFB or whoever?  It seems a lot of issues people have are solved with replacing parts that look pretty much the same.  It's almost like some ends of the tolerances fit some guns, and the other end others.  Based on the measurements JFB gave above, would not "tightening" up the tolerances just a bit all the way around tend towards more weapons functioning perfectly without some parts replacements?  Or are the tolerances now as "tight" as they can go without jumping to another level of technology (and cost) ?

    -Scott
     
  8. JFB

    JFB New Member

    Jul 25, 2005
    Reducing tolarances are $ (and time)....
    After posting, I got thinking about this particulair screw and how I would establish the proper clearance.
    ...When I get a chance I'll look very close and try to post my thoughs on this detail
     
  9. sgunsel

    sgunsel New Member

    9
    Oct 16, 2005
    Thanks for the quick responses.

    If the screw head socket wasn't stripped by the factory, I would have removed it. Presumably too soft.

    I don't think an allen wrench was provided in the box when the gun was purchased.

    BUT my question has been answered.

    Thanks again.

    Steve
     
  10. sgunsel

    sgunsel New Member

    9
    Oct 16, 2005
    Just re-read the above. Sounds like KelTec probably uses a 0.25 inch screw.

    Steve
     
  11. Wilson

    Wilson New Member

    Sep 7, 2004
    I hated the hex-screw too, until I acquired a high-quality 2mm hex driver (HoBao, flat not ball). IIRC, it was about $12 plus shipping but well worth it.

    In my opinion, the old style extractor system was far more attractive and worked well when the P-32 extractor was used in lieu of the standard P-3AT extractor. The first-gen extractor system did have more parts, required more time to assemble, usually required the owner to return it for service, and cut into company profits but looked better ::)

    Wilson – who’s cognizant of the fact that the hex sight screw is a hair shorter than the buttonhead and would never mix-up the two ;)
     
  12. Syndil

    Syndil New Member

    May 8, 2007
    Nope, not going to make a remark. Too easy. ;)
     
  13. Bobo

    Bobo Active Member Supporter

    Jun 13, 2005
    "Standard" screws are 1/4", 3/8", 1/2", 5/8", etc. long - the Kel-Tec button head screw is about 9/32" (1/32" larger than 1/4" and 3/32" shorter than 3/8").

    This is from measuring the screw I removed from my P-3AT and measuring two replacement screws that Kel-Tec sent me. For measuring I used a machinist's scale which is marked in 1/32" and accurate to about 1/64".

    So, to answer the original poster's question; a #6-32 x 3/8" screw with threads filed down to 9/32" should work just fine. It did for me except I filed mine down a bit less so I could include a lockwasher as in my long post with pics above.
     
  14. JFB

    JFB New Member

    Jul 25, 2005
    In the interest of knowledge (and I haven’t clean my firing pin in a long time) I pulled my firing pin and took the following measurement

    The groove in the firing pin is 0.077” deep
    The thickness of the slide’s threaded hole is 0.200” deep
    The thickness of the spring is 0.030”

    Thus the sum of above is 0.307”.  A screw any longer, say a 5/16 (0.313”) would bottom out and lockup the firing pin.

    The screw I removed from mine WAS 0.250”.

    Thus with the 0.200” threaded slide
    The 0.030” of the spring
    And the 0.003” clearance between the hole ID and the pin OD

    Thus the sum of the above is 0.233” means I only have an engagement of (0.250 – 0.233 =) 0.017”.  This was also indicated by the slight witness marks on the screw made by the firing pin impact.

    I installed the longest (0.275”) spare I had and wished I had one longer.

    Some other measurements
    The firing pin ODs 0.157” and 0.070”
    The drilled holes IDs in the slide were 0.161” (#20) and 0.073” (#49).

    BTW, my firing pin NEEDED the cleaning.  The paraffin/Teflon lube I used was gritty, hard and had to be reamed out.

    Thus to answer the original question.

    A 0.250” (1/4) is the minimum length.  If you do a lot of shooting, it would probably brad and fail

    A 0.313” (5/16) would need to be just a little short (need a little filed away).  If don’t clean your pin regularly, the tight clearance would gum up and fail

    A 0.281” (9/32) would be in a range that should work fine.  Enough engagement to take the impacts, enough clearance for a little grit buildup, and allow for a screw manufacturing tolerance.


    Thus KT could order #6-32 9/32 screws with a standard tolarance of + 0/- 0.0290.031" for a penny a piece.   BUT if they wanted a close tolarance of say 0.003", it would cost $0.25
     
  15. guru2sum

    guru2sum Well-Known Member

    Apr 30, 2005
    Mad City, Wisconsin
    As I recall, the tolerance on a standard screw would be +0.000/-0.031.  So a standard 1/4 long screw would be unlikely to be 0.250 long.

    G2S
     
  16. JFB

    JFB New Member

    Jul 25, 2005
    True,

    so the 0.250" I have ARE 9/32" (0.281") just at maximun tolerance

    I just wonder where KT finds 9/32".
    I can find 1/4" and 5/16".
     
  17. flonder22

    flonder22 New Member

    376
    Feb 11, 2007
  18. Bobo

    Bobo Active Member Supporter

    Jun 13, 2005
    Maybe Kel-Tec orders 1/4" screws and separates the longer ones for P-3AT extractors, and the shorter ones for PF9 sights?
    It would be a good time-filler for a slow day. :D
     
  19. JFB

    JFB New Member

    Jul 25, 2005
    I don't know. :-/
    From the few P3AT extractor screws I had. They just grab and hope for the best. that 0.235" would have been a problem If I had used it
     
  20. guru2sum

    guru2sum Well-Known Member

    Apr 30, 2005
    Mad City, Wisconsin
    So a 1/4" long screw would be in the range 0.250/0.219.  A 5/16" long screw would be 0.312/0.281.  A 9/32" long screw would be 0.281/0.250.

    If you order about 100,000 you can get whatever length you want, but the tolerance will still apply unless you want to pay for it.

    G2S