The guys that did the super accurate 416 HE did another
416 HE that has an 8" longer 42 inch K&P barrel..

Used a Stiller action and same load with 475 gr bullet, as in
first gun and and gained about 200 fps with good accuracy.
3065 fps. Tested 2 groups of 3 and less than 1/2 min moa.

And loads they used are not the highest speed loads
the cartridge is capable of....Here is print with specs for
the 416 HE reamer chamber ....Ed....