"your heavy barrel will not allow you to overpressure compared to other barrels, you should know that!"
What book did this come from this is a new to me ?
all of the max loads in all of the load manuals are under the true max
and all gun designs have to be pressure tested at 2 times their intended use to sale to the public.
a max load for one gun may not be in another
I had two 243 rifles and the max load in one was fine and the other it was hard to open the bolt after firing the same load.
a cartrige can have a pressure rating of 65,000 lbs and in the load book it will tell you the max load is 57,000 lbs, this is only because of libilities. not because your gun will expload
in your face.
(if you want your bullet to get there quicker then leave the house sooner)
accuracy is always more important than speed