From: bercov@bevsun.bev.lbl.gov (John Bercovitz)
Subject: Re: The Parker 10 mm
Organization: Lawrence Berkeley Laboratory, California

In article <50562@mimsy.umd.edu> davep@hpfcpp.fc.hp.com (David Post) writes:

#On further inspection we saw that the Parker did not have a feedramp, but a
#feed cone.  By design, the cone is positioned such that most of the bottom
#3-4 mm above the case head's groove are unsupported.

 3-4 mm!!!???  Are you sure?  That's an awful lot.

#This means that a large area of unsupported brass contains the combustion
#of the powder.

Right.

#I am no expert and I wonder what others think.  Is this dangerous?

You bet.  Most of us who have had case blow outs didn't enjoy it.

#What if
#aluminum cases are used?

Aluminum is generally about as strong as brass, it just doesn't have the
fatigue strength of brass so you can't reload it.

#Can these cases be safely re-sized in a reloading
#die?

What, the aluminum cases?  No, they can't be.  If you mean brass, resize a
case and then look/probe down inside it for a stretch groove.

#Would it have been more trouble to support the whole case with chamber
#steel?

Sounds to me like they had a feeding problem and they took the easy and
dangerous way out.  It's also possible that this gun is a fluke - it's
mis-machined and their inspection process didn't catch it.  Yet another
possibility is that some previous owner hacked it.

John Bercovitz     (JHBercovitz@lbl.gov)

From: bercov@bevsun.bev.lbl.gov (John Bercovitz)
Subject: Re: The Parker 10 mm
Organization: Lawrence Berkeley Laboratory, California

In article <51197@mimsy.umd.edu> post@hpfcso.fc.hp.com (David Post) writes:

#At a gun show yesterday, I took a look at some more Parkers, 2 in 10mm*, a
#40S&W and a 45 ACP.  They all have feedcones and they all LOOK like they do
#not support the case very well.  It is certainly a lot different that the
#Ruger P-85 or a SIGSauer.

#I would encourage anyone contemplating the purchase of one of these to drop
#an empty case into one to check this themselves.

The best way to do this , IMHO, is to take an empty case, saw longitudinally
half way down the case starting by splitting the primer pocket.  Then take
another cut perpendicular to the case which meets up with the first cut.
This removes a quarter of the case including half the case head.  Insert the
cut up case in the chamber until it bottoms out, and see if the thin part of
the case is supported or not.  Since my explanation of the sawing was lousy,
here's a lousy picher:


             _______
             |______|
             |____|
             |     \
             |______\
             |      |
             |      |
             |      |
       ______|      |
      |             |
      |             |
      |             |
      |             |
      |             |
      |             |
      |             |
      |             |
      |_____________|


I have found that different cases have different wall thicknesses near the head
so cut up a few brands before you decide which is your worst example.

John Bercovitz     (JHBercovitz@lbl.gov)