I can't edit my original post, but I found a couple more sites worth listing:
https://www.powderthrough.com/ I know nothing about this site, but it gives a lot of data for the most popular rifle and pistol cartridges.
https://www.shootersreference.com/reloadingdata/ This site combines data from multiple manufacturers into a single database. Very cool.
.38 Special data for snubnose revolvers Some useful .38 Special data.
