450 ackley, Just thought you might be interested in what I found while reloading the 416 Ruger,
I was using 2208 with 400 gr frontier bullets in my 416R Alaskan but found the load was compressed too much to get any more powder and velocity. Also I was not able to seat the bullet to the cannelure groove for a crimp. I switched to 2206H powder and now I am getting 2320fps from the 20" Ruger barrel with a slight crimp and less compression on the load.

I find the concept of free boring the 416Ruger interesting, dont know If there is enough space in the ruger magazine to allow for seating the bullets further out but would certainly help with pressures having a longer jump in the throat.