tenx wrote on Jan 13^th, 2012 at 8:36am:


I believe that the internal volume of the .32 Miller Short is very close, if not identical, to the .32-20 CPA.  With that in mind, I checked my old chrono data for AA#9 loads in the .32-20 CPA.

It required 11.8 grains of AA#9 to bring the extreme spreads down to single digits.  However, at that load, cases were very difficult to extract and they showed plain signs if incipient case head separation after a few firings.

With AA#9, maximum pressures increase dramatically with small increases in powder charge.  Considering the pressure-related problems I experienced with 11.8 grains, it's not surprising that you experience difficult extraction at 12.2 grains.

I think that you will be very happy with 4100.  However, even 4100 is not forgiving of loads exceeding 12.8 grains in the .32-20 CPA.  And, at maximum loads, you have to very careful of seating depth.

My cold weather load is 13.0 grains of 4100.  This is right on the ragged edge as far a pressure goes.  By backing-off seating depth by approximately .020", I can cause hard extraction with this load.

JackHughs   

tenx wrote on Jan 13^th, 2012 at 8:36am:


Quickload says that one is over 35K psi.   Not to wonder that cases are sticking.

uscra112,

Interesting and since you use .357 Mag., or .357 Max. cases that might be the cause of the sticking.Do you know what those cases are made to withstand in their respective calibers?

Pete

According to the Accurate Arms loading manual, the .357 Magnum uses a SAAMI maximum average pressure rating of 35,000 psi.  The Maximum is rated at 48,000 cup.  According to a sheet I've got from the old Hercules Powder Co., cup and psi don't always have the same relationship to each other...some cartridges have a much higher maximum cup rating than the same cartridge in psi, and with others it's the opposite.     There are lots of factors in determining why a particular cartridge sticks in a chamber or has other problems, pressure is only one part of it.   

David

Pete, pm sent.

David

JLouis wrote on Jan 15^th, 2012 at 7:53pm:


35KK is a bit steep for .32-20 cases, innit?   Did I miss something?  I thought that's what JackHughes said he was using. . . .   I know it's not for Max cases, I run those well past 40K in my Contender quite a lot.

Hard case extraction also has to do with certain rifles,for instance, the De haas "sometimes called miller" has a much better extractor than a Stevens.  ledball

Uscra the majority of all breach seated calibers being used have rimmed cases and are head spaced off the rim so case stretching / lengthening would have no ill affects. 

On a rimless case then your comment: Might that not point to more-than-optimum headspace? Yes that could indeed be a possibility 

J.Louis