From: bercov@bevsun.bev.lbl.gov (John Bercovitz)
Subject: Re: Proper extractor tensioning ?
Organization: Lawrence Berkeley Laboratory

In article <39018@mimsy.umd.edu> wa3wbu!john@uunet.uu.net (John Gayman) writes:

#   Is anyone familiar with how to properly tension the extractor on a .45
#1911 type pistol ?  I have one which is way too tight. I'm encountering
#some feeding problems to where the rim is obviously having a bit of trouble
#getting under the extractor. If you manually slide the rim under the 
#extractor you can feel the additional force. I've even taken the extractor
#out of another pistol and the gun then works flawless. 

#   A gunsmith advised me to simply bend the extractor to give the proper
#tension. My question is how best this can be accomplished. At what point
#do you actually do the bending and how fragile is the extractor. I assume
#its fairly hard. Will it bend slightly and not just snap in two ? I
#really don't want to chuck it up in the vise and start bending on it before
#I know exactly what to do. Thanks.

First of all, extractors are cheap, so you can buy another if yours gets 
too messed up.  Often one has to fit even brand new extractors because they 
don't fit quite right.

The extractor only needs to be bent slightly.  The metal in it's really 
not all that hard.  It doesn't need to be hard because it's a long 
spring with very little deflection as installed.  (You only need a hard 
temper in a spring to move the yield strength up on account of having a 
relatively large amount of deflection.)  So not to worry.  As far as how 
much force you need to have as a preload: that's an individual gunsmith 
sort of thing.  This is a really crummy answer, I know, but it indicates 
that the setting can't possibly be too critical.  I have heard of gunsmiths 
setting the preload force so that it takes 4 pounds force to push a 
slide-held cartridge case out.  I set mine so it takes about one pound.  
I've never had a failure to extract at this level, but my experience is 
limited compared to that of the professionals.  Do remember to make sure 
the extractor slot is bearing on the cartridge rim before trying to set 
the extractor force!  File on the pad if it's not!!  You can waste a lot 
of time otherwise.  8-)

Top view of end of extractor.

                    The hook area shouldn't hit the cartridge case
                    or the barrel when the slide is closed or it might
hook        __      get broken when the slide slams shut.
area ->    /  |     File on it if you have to to achieve clearance.
          /_  |    
slot ->    _| |     The bottom of the slot is what should be touching
pad ->    |_  |     the case rim.  I like to remove some pad as 
            | |     necessary until the extractor is moved about .010" 
            | |     upon insertion of a case.
            | |
            | |     Bend in this area.  Gently - long radius bend.  
            | |<-   (You remember Gentle Ben, right?  Good.)
            | |     If you need more bend, bend immediately on the
            | |     other side of the bump too.
bump->     |   |   
            | |
            | |
           ~~~~~


Interior view of end of extractor.

                __     It helps feeding if you radius or ramp (~.04")
hook ->        |  |    the two areas pointed out in the sketch at left.
radius hook -->|__|    
radius slot -->|__|     
pad ->         |__|       
               |  |      
               |  |     
               |  |
               |  |     
               |__|     
bump->         |__|    
               |  |
               |  |
              ~~~~~~


Another view of the same thing:
Enlarged cross sectional end view of end of extractor, slot area.

 <---  down   up ---->
        ________
       |        |
       |        |
       \        |
        \_______|
       ^
       |
    Radius or ramp here.


Another one of Peculiar John's Tiring, Pedagogical Idiosyncrasies:

I guess the sense in which gun-rag writers use the word "tension" must 
be along the lines of tension as in "high-tension wire".  Or maybe it 
stems from Galileo Galilei's (What's Galileo Galilei mean anyway?  
Galileo Junior?) incorrect analysis of the bending failure of beams - he 
thought that the materials in beams could only fail on the tension side of 
the beam, this because he thought that solid materials are all 
incompressible.

Today tension means to stretch, compression means to "squarsh", and 
torsion means to twist.  With these definitions, we can tell the three 
common types of music wire coil springs apart.  Incidentally, tension 
and compression coil springs deflect under torsion-induced shear, if you 
think about it (Of course they also do if you don't think about it, 
fortunately.).  A 1911 extractor is a kind of leaf spring; it is sorta 
like a cantilever beam.  Here we usually talk about spring deflection.  
When deflected, one side of a leaf spring is in tension and the other is 
in compression.  Clearly, by any engineering definition of the word 
tension, gun scribes are using this word wrong.  I don't know what the 
correct wording would be for adjusting an extractor, but it ain't 
"tensioning".

    JHBercovitz@lbl.gov    (John Bercovitz)