no 2 chambers are exactly alike, no 2 barrels are exactly alike, no 2 bullets have the exact same bearing surfaces, the exact same load will not make the same pressure or velocity in any 2 rifles.
and to top that off the safety buffer some manuals have for liability purposes are different. You can even find differences in different versions of the same manual. all a manual is is a reference to get you safely started, I always work up and find a max load for my rifle then back off to a safe level.
RR