|
CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
The way that the 357 magnum was developed was to take a 38 special, and increase the powder charge until the cases stuck. Then back off a small safety margin and that is the 357 mag.
Years went by.
They tried to measure the pressure and register it with SAAMI.
Then someone made thin chamber wall 357 mags, and factory ammo would get sticky cases.
So they reduced the SAAMI registered pressure.
Then they came up with new ways of measuring pressure.
In 1999 Midway published 357 mag loads that were lower than 38 special loads published by Speer in 1964.
They used an "Oehler System 83 and piezoelectric transducers, the latest in industry standard equipment".
Here are some of my experiments:
Put a .380" straight fluted reamer into a S&W model 60 38 special and reamed each chamber in the cylinder out to 357 mag length.
1) Alliant load guide says 9gr max Bullseye for 110 gr. JHP 357 mag.
I did and the case stuck. Backed off to 8.7gr and the case was free.
2) Hodgdon load guide says 22 gr. maximum for H110 125 gr. JHP, wspm.
I did and the primer squished into at top hat.
3) "Midway Load Map" says max 357 mag load is 13 gr. AA#9 158 gr. JHP.
"Lyman 47th" says 16 gr.
I did 17 gr. and the case stuck bad.
What does it all mean?
H110 gave me the most power in 357 mag, without stuck cases.
|