Ok, so with the current shortage of .38 special brass going on, I was wondering if I could use some .38 Long Colt and Short Colt brass loaded with standard Bullseye. I know they both have ample space for the 4.2 grains of Bullseye, but I was wondering if perhaps the distance between the powder and bullet would cause a pressure spike. Thanks!

I didn't know there was a shortage of .38 Special brass.
38 Long Colt brass is a little wider than the .38 Special but more importantly, it's shorter too. I'm guessing if it were life and death I would use it but I also think 38 Long Colt brass would be much more rare than 38 Special brass. I'm betting if you put that brass up on this site for trade you will get many takers.

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Pressure changes with OAL, how much so isn't know unless you have a piezo transducer on a test barrel. I wouldn't recommend using data for 38 spl in a smaller cartridge.

For short colt you can use reduced (15-20%) 9x19mm load data and work up, lots of people have done that for ICORE loads.

Thanks guys! I think I might try the 9x19mm load data method and the thing is is that most websites are sold out of .38 special brass, but they have short and long colt readily available.

There is reloading data available on the Hodgdon reloading site.
for the 38 Colt long and Short.
But these will be for Winchester/IMR/Hodgdon brand powders.
http://data.hodgdon.com/main_menu.asp


What I used to do,,,,and this is just fyi
I used to seat the bullet in the shorter 38 Long Colt case so that the cartridge OAL is the same as the 38Special loaded with the same bullet,,,you'll leave the same powder space inside.
A loading that is safe in the 38Special loading would be presumed safe in a 38Long Colt so loaded.

A full W/C seated flush in a 38Special will be seated so that about 1/3 of the bullet is forward of the case mouth in a 38Long Colt.
DON'T seat the bullet to the crimp groove using 38Special data in the shorter 38Long or Short Colt cases.
Allowing for small variables in brass thicknesses,,as always, begin with the 'starting load' and work up.