i think there is some confusion.
the xlr question 1630 bar is what the gun is proofed too, not what standards of shells that should be used in it.
these high performance loads have a higher pressure rating to take full advantage of the range of powders available.
they also have other criteria, of ptmax (pressure threshold ) and upper deviations of pressure fluctuations, both the PTMAX criteria have a maximum of a shell producing ptmax * 1.15. this equates to about 800bar and 1200bar respectively. i get this from 740 bar multiplied by 1.15.
the average pressure must be below 740 or 1050 respectively with no shell exceeding 1.15x the ptmax. so there is some fluctuation in pressure acceptable. these modern guns are superiour proofed to extreme standards.
as fot the proofing having limitless, is a moot point, because if the magic (speed) isnt happening at 10,000psi, 10,770 psi isnt going to do it. thats the point. the 3.5" saami specs are 14000psi and that is a great deal higher than the standard proof. it may work out the extra 3-4000psi would clean up that load, may or maynot make it faster, but i can assure you, nearly all powders burn clean at high psi and if the pressure peak is extended for about half a millisecond or so.
these super slow powders such as "steel" need alot of pressure to get them clean, pressure is the burn, the powders burn slow giving there energy over a longer period of time, these slow powders give alot of pressure over a longer time . in ballistics thats only an extra 0.5 microsecond or so. but the main peak must be below the maximums.
now what does this higher pressure rating do? well, it gives us the chance to use up all the powder (fuel) in the reaction. this should mean the pressure variation is lower because all the fuel is efficiently used and that end result should be the fps is more consistent.
i know a few reloaders that use the HP shells for wildfowling, but they are using european powders.
now in your case the cip proofing is meaningless, just grab a great recipe from a manufacturer, such as hodgdon and alliant. because there recipes are good and safe.
i proof alot of loads, i have more failures at proof, but i`m doing experimental stuff.