I was about to say a chronograph will be much more useful than 357 Magnum data when trying to develop a .38 Special +P load. If there is no data for a certain bullet or powder in the .38 Special +P it's possible using those bullets or powders is not recommended. BUT, like said above, there is tons of .38 Special +P data in manuals and online.

What are you trying to load and maybe we can help you? Which bullet, bullet weight, brass, primers and powder are you using for that .38 Special +P load? I have several good loads I worked up a few years ago that might fit with what you are doing.

__________________
Freedom is never free!!
SWCA #3437