>If you are loading handgun cartridges and you find a recipe in loading book "A", which is identical in every respect, except powder charges, to a recipe in loading book "B" and you are not changing handguns, which recipe would you use?
When I started reloading (~1973), I started with 9x19 and .44 Mag. Twice, I started at a manual's start load and, in my guns, the loads were max or over-max. I decided then and there that NO manual was perfect and I got several.
Since then, I also review my manuals and start at the lowest starting load and work up. I have found many times that the Max load in my guns was well below the highest max load in a specific manual and, occasionally, it was below the STARTING load in one manual.
Because of this, I started to enter reload data into an Excel spreadsheet so I could easily see the start and max loads and start low and work up.
Thus, my "rule" is that all reloading manuals are absolutely correct: for the gun they used, the lot of powder they used, the brand and lot of bullets they used, the cases they used and the primers they used. I don't have any of those, or can't verify that I have those, so I start at the lowest start load and work up.
If you want to be safe, do this.