38 and 357 wadcutters - load data confusion

[plinkr]

Hi folks, I have a question for the more experienced hand loaders out there. I have loaded 38 Special wadcutters (148 grain) for years and became curious about loading them in 357 Magnum (looking for a bit more velocity). Using Titegroup as an example, the Lee manual gives a maximum load for 38 Special as 3.3 grains for 908 fps and 11,800 psi. For 357 magnum the maximum load is 3.3 grains for 909 fps and 18,900 psi. With the same load and the same powder in a bigger case I would expect a lower pressure and lower velocity. Can anybody help me understand this?

 

[benenglish]

My Lee manual is old enough that it doesn't show Titegroup. It also shows vastly different maximum loads for the same powders when switching between .38 Special and .357 Magnum. As might be expected, the max .357 loads shown are listed with much, much higher velocities.

Does your manual show different powder charges and velocities when using powders other than Titegroup?

 

[plinkr]

It gets worse. Max loads for 38: 4.0 (Win 231 & HP38), 956 FPS AND 15,900 PSI. Max loads for 357: 3.4 (Win 231 & HP38), 908 FPS AND 17,600 PSI. Wierd.

 

[TheMailMan]

The Lee manual is a compilation of data from other sources. They don't test anything.

Why not use the data from Hodgdon? It's where Lee got the data?

You would note that the .38 Spl uses a standard primer and the .357 Mag uses a mag primer, also the .38 uses a 7.7" barrel and the .357 uses a 10" barrel.

That primer apparently makes a difference in that load.