ake your pick...
You stick XX grains of Bullseye in a .38 spl case under a 125 grain bullet & stick the same amount in a .357 mag case under a 125 grain bullet & you'll get pretty much the same velocity out of both.
On the upper end, stick XXX grains of 2400 in a .38 spl case under a 173 grain cast lead bullet & stick the same amount of 2400 in a .357 magnum case under the same 173 grain cast lead bullet & you get pretty much the same velocity.
That's more or less what Keith did back around the early 1930's.
Hal is offline Report Post Quick reply to this message
Had to borrow a test barrel and transducer to do this
8" barrel and PCI transducer used in Willams reciever, Ohler 87
125 XTP Hornady bullet and Bullseye powder
Tested each set to get as close to SAAMI MAP pressure for each cartridge
38 case, measured pressure 17100psi, measured velocity 1205fps (5.6 g)
38 case, measured pressure 18408psi, measured velocity 1272fps (5.8 g)
357 case, measured pressure 34875psi, measured velocity 1577fps (8.2 g)
If you load to MAP for any reasonable powder your results will be similar.
Case volume matters, pressure matters.
A 38 is a 38, a 38+ is a 38+, a 357 is a 357.
You cant make something it's not no matter how hard you try.
be safe
Ruggy